Stag Party

A guy is getting married, and on the night before the wedding his friends throw a wild party to celebrate his last day as a bachelor. It gets wild, often having a lot of beer and smoking. Sometimes they'll also go to a strip club or hire a stripper for the party. Occasionally, the bride-to-be (or the wife of one of the invited, in some cases) will walk in on the party and be horrified at this aspect -- or it turns out her bachelorette party is as raunchy and over-the-top as his party is, or more.

Somewhat of a Truth in Television, although it rarely ever gets as serious as above.

Compare Wild Teen Party.

Examples of Stag Party include:

Film

In Fantastic Four: Rise of the Silver Surfer, shortly before Mr. Fantastic and the Invisible Woman's wedding, Mr. Fantastic, under The Human Torch's suggestion, went to a dance club for their bachelor's party. Eventually the Invisible Woman and some of her friends stumble upon Mr. Fantastic talking it up with some of the female dancers.

Live Action TV

Inverted in the episode "Mr. Monk and the Big Wedding" of Monk, where it was a bachelorette party. Basically, the party had the women hiring a male stripper (in cop uniform), where he asks the hostess if she has been a bad girl. However, it had to be cut short because Monk arrived to take Natalie, as one of the people at the mud baths discovered a dead body in one of the stalls, also taking the stripper with him (having mistook him for an actual cop, with the latter being at least familiar enough with cop-terms to understand the seriousness of the situation.)
- Played straight and deconstructed in "Mr. Monk Is the Best Man", where Stottlemeyer let Monk plan the bachelor's party, and it was exceptionally bland, even leading to an inversion of the Designated Driver trope due to Monk only supplying one 12 oz. beer bottle to each guest (making 144 oz. total, as there were 12 people in attendance). The closest it got to being a serious party is when someone firebombed Stottlemeyer's car, something that an extremely drunk Disher reported to Stottlemeyer about someone illegally parking a charcoal-black car with "flames painted on the windows."

Newspaper Comics

In one FoxTrot cartoon, Roger remarks reluctantly that he brought home a souvenir from a bachelor's party that he earlier claimed was boring where they drank and told jokes. It was strongly implied that Roger actually went to the Playboy Mansion and that he took one of the Playboy Bunny's rabbit ears, to which Jason, obviously not knowing what the ears were originally for, wore them to celebrate Easter.

Western Animation

The Simpsons had Homer Simpson attending a stag party where he, while drunk, danced with Princess Kashmir, an exotic dancer, an action that Bart stumbled upon while making his way back from the bathroom in the restaurant (It Makes Sense in Context) and photographed. It's technically a deconstruction, however, as the host and his father clearly did not want that kind of party, and yet somehow managed to get them anyway.
A Stag Party was a pretty big part of the premise of Family Guy's pilot episode "Death Has A Shadow." Unlike most examples, the major consequence of his going to a Stag Party doesn't involve losing his marriage or having a strained soon-to-be-marriage, as it is that Peter loses his job thanks to negligence via sleeping on the job.