Obligatory Joke

Superman: Is everything okay?
Wonder Woman: Well, I'm sort of missing Flash's obligatory joke about Grodd having made a monkey out of us.
Superman: Just couldn't let it go unsaid.
Wonder Woman: Obligatory!

—Justice League Unlimited, "Dead Reckoning"

In certain situations, characters (and writers, it seems) just have to make certain puns. And they're usually the same ones. But Tropes Are Not Bad, as in many cases the audience may feel disappointed or even slightly confused if the obligatory joke fails to come up.

Nonetheless, many writers try to inject some freshness into the obligatory, by lampshading or overt and deliberate subversion.

Anything involving a primate is going to involve lines like "Monkeying Around" or Making a Monkey('s uncle) out of someone," and "Monkey Business".
- We're just going to make it easy and say that whenever a situation with an animal comes up, somebody will have to quote a saying or phrase having to do with it.
Anything involving honey, molasses, maple syrup, etc. will be described as a "sticky situation."
A person Bound and Gagged, or even just bound, will be described as "a little tied up right now."
If an animal of some kind is biting someone, an onlooker will be prompted to ask, "What's eating you?"
Any hand-related pun when dealing with hand monsters or armless people.
Cat-related jokes are sometimes catastrophic or catholic. They may leave you catatonic.
Any time electricity is involved, you know someone will quip about a "shocking" situation.
Similarly, expect An Ice Person to be surrounded by an abundance of "Ice to meet you," "Take a chill pill," etc. jokes.
Whenever identical twins appear as part of a main cast or as recurring characters, someone will eventually ask who the older one is, even though this is only truly important if they are royalty.

See also Incredibly Lame Pun, Bond One-Liner, Quip to Black, and others, which have considerable overlap. You Look Like You've Seen a Ghost is one subtrope. A Punny Name or Unfortunate Name resulting in this may make someone a Phrase Catcher.

Examples of Obligatory Joke include:

Comic Books

The Spectacular Spider-Man had Green Goblin do the "tied up" joke, chuckling to himself that you gotta love the classics.

Fan Works

Sirius Black taking every opportunity to make "serious"/"Sirius" puns in Harry Potter fanfics, to the point that in many later works, the characters start out already tired of them.

Film

Meta-example, Stan Lee is certain to make a Cameo in every Marvel Cinematic Universe movie for as long as he is able.
Every film (and some Expanded Universe stories) in the Star Wars franchise will have someone Tempting Fate by saying, "I have a bad feeling about this."

Literature

The Dresden Files: To hear Harry Dresden tell it, he's the original this. He claims that he's now so well known that if he isn't flip and punny to every supernatural being of a distinctly higher weight class than him, they'll be insulted, because they expect him to be. Note that this was a retrospective excuse to Sigrun for pissing off Odin's secretaries.

Live-Action TV

On QI, giving the obvious-but-incorrect answer causes an alarm to ring and the panelist to forfeit points. Obvious riffs such as these sometimes trigger the klaxon as well.
Castle uses the "tied up right now" variant when the eponymous character had bound himself to a chair to see whether he could free himself. Played with in another episode Lanie finds out that the recent victim, who had been burnt in a pizza oven, has the last name "Burns". She tells Castle, who had started to look excited, to make the Obligatory Joke...but it turns out that Castle had actually recognized the name.
After the first act of the Jaye P. Morgan episode of The Muppet Show, where Morgan wears a ruffled bird outfit, we have this exchange between Statler and Waldorf:

Statler: Ooh, Jaye P. Morgan is terrific!
Waldorf: Yeah, but that last number was for the birds!
Statler: You had to make that joke, did you?
Waldorf: Well, one of us had to, and I lost the toss!

Newspaper Comics

Michael Caesar of The Boondocks often makes obligatory bad jokes about current events or whatever the topic of the day is about. His best friend Huey's response is usually to stop and glare at him, and then walk offscreen without saying a word. Caesar usually quips that he needs a better audience.

Web Original

Yahtzee's review of No More Heroes opened with the song "No More Heroes" by The Stranglers, which he cut short stating it was too obvious.
The Nostalgia Critic did a review of the Care Bears movie, and when the leader of the Care Bear Cousins said his name, Braveheart, Critic showed a clip from Braveheart, asking how could he not do that joke. Later, he opened a review of the film Alaska with "Sarah Palin is stupid. That's my obligatory Sarah Palin reference out of the way. Now, Alaska..."

Web Comics

On this page of Dinosaur Comics, T-Rex complains about the overuse of the phrase "a whale of a good time" in conjunction with literal whales.

T-Rex: It should mean "a good time that is large or immense: METAPHORICALLY like a whale", but the metaphor's broken because it's always used on literal friggin' whales. "Dog-gone great" is getting there too.

Western Animation

In the Danny Phantom episode "Doctor's Disorders", Penelope Spectra tries to get a sample of Danny's DNA to make a perfect body for herself. When she's not looking, Danny swaps it out with something from his dad's uses hankerchief. The result is Spectra turning into a Jack Fenton-shaped snot monster. Danny comments, "There's a 'You blew it' pun here somewhere, but I'd rather not." When the fight begins, Spectra growls, "Let's boogie!" to which Danny replies, "That's exactly the kind of pun I was trying to avoid with the 'You blew it' comment!"
In a particularly silly episode of The New Batman Adventures, Robin and Batgirl are fighting genetically altered giant cows. Batgirl lampshades the fact that Robin couldn't resist yelling "Holy Cow!"
The page quote was used in Justice League after the heroes foiled Gorilla Grodd's plot to turn all of humanity into gorillas.
In one episode of Kim Possible, Kim discovers that the villain keeps electric eels, to which she replies, "The puns just write themselves. Shocking, isn't it?" Of course, the villain says the very same line later when he reveals his electric eels.
In the Garfield and Friends (U.S. Acres segment) "Secrets of the Animated Cartoon", Orson explains that it is required by law to do a a take whenever you're scared, and then goes on to explain Double Takes, Spit-Takes, and Delayed Reaction Takes. In the next scene he claims that a chase scene in a cartoon also requires the Painted Tunnel, Real Train gag.
In every version of Teenage Mutant Ninja Turtles, someone will, at least once, use the word "rat" in a negative way, and then have to apologize to Splinter.

Video Games

It's lampshaded in Strong Bads Cool Game for Attractive People episode 5. Homestar is in a dungeon suspended by his "arms". Strong Bad asks him what's up:

Homestar: "Oh, you know, not much..."
Strong Bad: (sighs) "You can say it, Homestar..."
Homestar: "Just hangin' around."

Starcraft has a meta-example. If you claim it's War Craft In Space, someone is sure to counter this claim by saying, "it's far more sophisticated!"