Gay Bar Reveal

"Wait a minute... There's something bothering me about this place... I know! This lesbian bar doesn't have a fire exit! Enjoy your deathtrap, ladies!"

—Homer Simpson, The Simpsons

Manfred M. Manly wanders the streets looking for a burly bar where he can makes a Drink Order of his favourite Gargle Blaster, proposition women with crude sexual Double Entendres and watch manly high impact sports on a 30 year old television before establishing alpha male dominance by engaging in Greco-Roman wrestling with other patrons.

He finds himself a bar or club with broad strapping patrons, perhaps full of bikers or steel workers, deep bass music and tall erect steel bars for extra manly effect.

But wait, what's that? A series of short sudden close ups on each of the elements of the bar have revealed the truth. Those manly steel bars are for pole dancing, the bass music is techno, the bikers and steel workers seem to love their leather, and that ain't Greco-Roman wrestling they're engaging in...

Manfred M. Manly has just had the Gay Bar Reveal. He has walked into a bar or club ignorant of its nature and slowly realises that it's a gay bar. It normally only happens to the character most likely to freak out about it, sometimes they'll actually be accompanied by someone who does get it quicker than them or even lead them there who provides a foil for the few moments before they catch on. Sometimes Manford will have the conspicuous homosexual elements pointed out to him but automatically imagines it to all be part of manly bonding.

The bar itself can vary in terms of its queerness. At one end of the scale it can be completely inconspicuous until someone points out that there are only male patrons and a few of them are holding hands. The bar can often at the point of the Gay Bar Reveal suddenly become a lot more obvious, with visual cues only actually appearing when the director wants us to see them. On the other hand, the trope can be frequently parodied by so obviously being Where Everybody Knows Your Flame that it makes the surprised patron look stupid.

Examples of Gay Bar Reveal include:

Comics

In the beginning of the "Half a Life" arc of Gotham Central, almost a full issue before the Reveal, Brian Selker (Private Detective) is following Renee Montoya to a restaurant called "Maloney's," taking intrusive pictures for a lawsuit that is about to be leveled against her. Being a long-distance shot in a comic book, with hand-drawn lettering instead of typed, there is not a lot of detail to be made out about the restaurant, and the name almost seems to be drawn as an afterthought: Maloney's Bar & Girl. It is not a typo, it is a revelation, and if you missed it you need to wait until the end of the issue to get the full story.

Fan Fiction

In the Zelda AU fic "The Weekly Hyrule News", Link, Ralph, and Kafei all go to an unfamiliar bar to engage in a little underage drinking. Link catches on pretty quickly that there’s a reason all the patrons are seemingly either “alone or with a friend,” and gets a kick out of watching the other two react once they figure it out. Kafei wants to leave, but Ralph convinces him to stay when he points out the lesbians in the bar.

Film

In Fanboys, in which a Bad Guy Bar out in the middle of nowhere turns out to be a gay bar—which the main characters realise after one of them casually uses a homophobic slur in front of the bar's many large musclebound patrons.
The bar where Stifler shows off his dancing skills in American Pie 3. This being Stifler, he didn't realize which kind of bar it was until the others told him to look around and pay attention. "Oh. My. GOD!".
Done with masterful subtlety in The Crying Game.
But I'm a Cheerleader has a scene where the rest of the kids at the True Directions camp (a Christian based camp where gay kids go to be 'cured') are leaving for the night to 'go have some fun.' The lead character Megan doesn't realize where they're going, and even though the outside of the bar has a huge rainbow sign that says 'The Cocksucker,' it takes her a few minutes to catch on. Megan questions why they went to a gay bar when they're trying to stop being gay, while the other campers point out, "Where else would we go?"
One of the more famous examples is the Blue Oyster Bar, a Running Gag from the Police Academy movies. Jerkass characters will oftentimes be tricked into heading there, only to end up in the tight embrace of Manly Gay bikers.
Chasing Amy had this in the second act. It's a double-whammy for the protagonist, as this is how he finds out the object of his affections is a lesbian, complete with alarm klaxons!
Wayne's World 2 features a scene where Wayne, Garth, and two of their friends disguise themselves as a construction worker, a police officer, a biker, and a sailor to spy on Wayne's girlfriend. When they are discovered they take cover in an establishment called "The Tool Box" which turns out to be a gay bar. When the DJ sees what Wayne and company are wearing, he shines the spotlight on them and cranks up the Village People's "YMCA" which leads to a hilarious scene where the heroes perform the dance associated with the song.

Literature

In Demon Blues by Esther Friesner, one of the straight characters stumbles into one of these crying about the girl he can't get, proceeds to get so drunk he doesn't catch on, and when the bartender is worried about him, gets taken home by a chivalrous time-traveling Richard the Lion Heart. He pieces it all together the next morning.
Happens in My Sister's Keeper, when Julia goes to a bar. When she asks if it's a gay bar, the bartender sarcastically replies, "No, this is a bar for cops."

Live Action TV

In an episode of In Plain Sight. While helping Mary clear one of her witnesses of a murder, Marshall visits the victim's favorite bar and talks with the bartender, who mentions that the victim always stood by his people. After wondering what that means, a confused Marshall looks around and realizes that all the patrons were male and many were holding hands...
One episode of NCIS Tony and Kate were questioning a bartender about a murder victim. Tony starts hitting on the bartender while Kate realizes it's a lesbian bar.
In the Murphy Brown episode "The Anchorman", Jim Dial fulfills his dream of opening a classy English-style pub, and it quickly becomes popular among the gay crowd. The trope is averted in that the customers are never shown as oversexualized leather daddies or weird crossdressers; Jim only realises what's happened when someone points out to him that all of his customers are men, and some of them are holding hands. Otherwise, it's just another spot where businessmen go to socialize after work.
Filthy Rich & Catflap: Richie and Eddie enter a typical British pub looking for 'working class costermongers' to kill Richie's father for him. When they are unable to interest the two men at the bar in the job, they start insulting their bravery and masculinity with homophobic slurs, concluding:

Richie: ...Bloody fairies! That's what you are, isn't it?
Men at bar: Yes.
Landlord: This is a gay pub.
[Cut to Richie and Eddie being hurled out of the pub]

An episode of Coach had this. The title coach (of American football; guess his attitude) ended up concerned that one of his students (I don't remember if he was a player) was less than heterosexual. He ends up in a peaceful bar talking with the student, and everything is fine. A slow dance tune comes on, and two young people go to have a quiet dance on the floor behind Coach Fox. They have a gender in common ...
- Played surprisingly straight considering the premise of the show and the time it was made, and still managed to be funny. The bar patrons in the reveal are just regular guys, not an assortment of stereotypes. Coach Fox is uncomfortable with the situation, but not freaked out or horrified. He agrees to treat the football player (Terry) like any other player on the team. For starters, a player in training is not allowed to stay out late, so Coach offers to drive Terry home. A couple of other players recognize Coach Fox leaving with the young man. The dialogue goes something like this:

Said Other Players: Coach! What are you doing there?
Coach (awkwardly): Oh...uh...I'm just taking Terry home. (Realizing how that sounds) Damn!

Played "straight" on The Parkers. When Nikki and her friends investigate Professor Oglevee's shady new girlfriend, they track her to the bar where she works and comment on the lack of men there. When the bar's manager informs them that yes, the girl in question is gay and yes, the bar caters to lesbians, Nikki and her friends react as if told it was the fifth level of Hell. One would think Mo'nique would know better, considering comedienne's large gay following.
Parodied on the UK sketch show Goodness Gracious Me. Two underage boys want to be served drinks in a pub, so to look older, they wear glasses (and can't see a thing.) When they remove the glasses, they realize it's actually a gay bar full of Village People lookalikes, and run away screaming.
Played with in this promotional pic for Glee from Rolling Stone—it's obviously a Manly Gay hangout, but it's more "Wrong Gay Bar Reveal" as the hapless patron is Kurt. (Saved from Unfortunate Implications by the regulars not looking predatory but equally dubious about him.)
- Maybe the other bar patrons just noticed the guy with the martini was underaged.
Its Always Sunny in Philadelphia does this to the gang in the first episode... with the added twist that the gang owns the bar.
One Mad TV sketch had Miss Swan end up in a "monkey in the bush" bar. She led them in a rendition of Dancing Queen.
Will and Grace had an episode where Will and Jack had to babysit Karen's mother-in-law when they already had tickets for the opening party at a nearby gay bar, so they take her along. The poor, senile old lady didn't realize where she was until it was too late...
In the Only Fools and Horses episode "Go West, Young Man", Del and Rodney go to a wine bar, and while Rodney has his drink, Del tries to chat up two characters in dresses we only see from the back. He quickly returns.

Del: Drink up, we're leaving.
Rodney: Yeah? Are they a couple of ravers?
Del: No, they're a couple of geezers!

Happened on 3rd Rock from the Sun. Twice, actually. The first time, the aliens walked into an obvious gay bar and Sally cluelessly picked up a man who mistook her for a drag queen. The second time involved a misunderstanding in which Dick thought he had discovered another alien, but had actually been Mistaken for Gay. Soon, Dick was hanging out at the local "alien bar".
Referenced in Leverage. Eliot is questioned about a bruise on his face and replies "how was I supposed to know it was a lesbian bar?" The incident is never mentioned again.
Referenced on The Mary Tyler Moore Show when Ted suggests ways for Lou to get more customers at a bar he bought.

Ted: I was in this bar that hired good-looking guys as waiters. I guess that's how they get women to come in. Though come to think of it, there weren't any women in that bar. Everyone there was a good-looking guy.

Western Animation

Played for laughs by The Simpsons; Homer, having been banned from Moe's and looking for a new watering hole, is the only man in a very obviously lesbian bar, providing the page quote, which is followed by a woman asking "What's her problem?" as he leaves (though this is a subversion, as Homer was fully aware that he was in a lesbian bar).
- Also on the Simpsons episode "Homer's Phobia" (where Homer makes friends with a kitschy antique store owner who looks like [and is voiced by] John Waters, but breaks off the friendship when he finds out that John is gay and Bart may be influenced by him), Homer takes Bart to a steel mill, intending to straighten him out by showing manly straight guys at work. However it turns out to be a gay steel mill that turns into a gay dance club/bar after the work day is over.
- It gets flipped around in the episode "Days of Wine and D'oh'ses">

Moe: Well, the handwriting's on the wall. To stay afloat, this bar's going to have to go queer.
Camp Gay Bargoer: You mean it's not? Ugh. Wrong again,"Gay Guide to Springfield".

- A planned but scrapped joke in "Flaming Moes" had a couple of gay guys entering Flaming Moes thinking it was a gay bar and leaving disappointedly. The censors wouldn't allow it.
Family Guy: after the Drunken Clam shuts and is replaced by a British pub, Peter and his friends start looking for a new place to hang out. They eventually come across a lesbian bar called The Cherry Pit, and seem quite happy that they have good sports on TV. Upon realizing that the girls at the bar are not making out because they're lonely, they demonstrate something like the 5 stages of Grief in regards to male comprehension of Lesbianism (surprise, arousal, rejection/dejection, acceptance) then leave. Quagmire takes the time to throw in a penetration joke, of course, and gets punched all the way out the door and onto the curb.
- In the same episode the trope is inverted when Peter mistakes the newly British Clam for a gay bar.

Web Comics

Inverted in Ménage à 3, where Sandra and DiDi go into a bar to talk, notice that there are mostly man there and conclude that it's a gay bar. It's actually a strip club.