So, I was just watching Night Shift again, and enjoying it as always. There's a scene towards the end, in the beach night club where Henry Winkler is getting in trouble. Michael Keaton is up on the top level and yells "I'll save ya Chuck!" and launches himself over the railing. The next scene is Michael Keaton thudding to the floor. I nearly busted a gut laughing at that the first time I saw it way back when, but not even a chuckle anymore. Obviously, it's only funny when unexpected.

I can think of a couple of other jokes that work on the same level (only funny once). Like in The Sure Thing when they're trying to break into the trailer to get out of the rain and Daphne Zuniga says "I have a credit card! Oh, but my dad said I can only use it in case of emergency". John Cusack, perfectly deadpan says "Oh. Maybe one'll come up".
The other is Chasing Amy, the beginning at the comic-convention panel where Hooper X is going on his blacks in Star Wars rant and says "They're saying that deep inside, we alls just wants to be white" and Banky asks "Well isn't that true?" Again, only works the first time.

Any other ones you can think of?

What an odd idea for a thread.

Obviously, all your (the OP's) examples are completely subjective in nature.

You claim that the joke in The Sure Thing isn't funny upon repeat viewing, but just your description of the scene reminded me of Cusack's delivery of the line and the look on his face, and I thought it was funny.

Theoretically, since humor should depend on the surprising and the unexpected, no joke should ever be funny the second time around, but obviously that is not true.

It would probably be really interesting to hear some very smart person explain how it is possible that we can be brought to laughter after repeated viewings of the same comedy.

Spaceballs. Everything.

The hair gel scene from There's Something About Mary

A big laugh the first time seeing it, but never laugh at it again on repeat viewings

This is a perfect example, as I would say any shock humor rarely works on repeat viewings. Jason Biggs fucking the pie is another example from American Pie.

The Keaton falling scene in Night Shift is still funny. You can go to the Dickens!!

Mallrats and every joke within. First time i watched it i really liked it (mainly for Jason Lee being pretty damn funny). Tried watching it a couple of times in recent years and its just unwatchable trash. I think this goes for most of Kevin Smiths work though.

I remember laughing my ass off at the end of Little Miss Sunshine on my first viewing, it diminishes once the "surprise" is gone. Still entertaining though.

Memento.

It wasn't funny the first time. Unless you were 5 years old.

I think this is just the case for most comedies. When you see it for the first time, it's unexpected. This makes it more funny. The same thing happens when they put all the funny gags in trailers (which you may have laughed at then)... By the time you see the movie, you may have seen that trailer 5 times already, so the gag is no longer laugh out loud funny.

It also depends on your setting. I can watch a hilarious comedy by myself and not laugh once through out. I may still think the movie is funny, but I don't necessarily show it. I can then go and watch that same movie surrounded by a group of friends, and actually let out laughs.

I like the movie, but I never found that scene funny.
IMO, Matt Dillon steals the film and his scenes are the funniest.

Spaceballs was awesome.

Pretty much. One thing that I always find funny regardless of how many times I see his movies would be Bill Murray's expressions.

Spaceballs was funny when we were younger, and now when my wife and I watch it, we may not be rolling on the floor laughing, but it's comfort food. And it's still endlessly quotable. So the jokes may not be "ha ha" funny on the 87th viewing, but if it's at least moderately well written it's still "fun" to watch something like it, if not "funny".

Schindler's List isn't nearly as funny the second time through.

I find that gag humor doesn't hold up, e.g. Woody Allen's "early, funny" movies (BANANAS, TAKE THE MONEY AND RUN) and some of the Marx Bros. flights of fancy, but that character comedy does, e.g. W.C. Fields pictures like THE BANK DICK and Doris Day/Rock Hudson (PILLOW TALK, LOVER COME BACK).

All of those M. Night Shamalyan comedies.

Every single bit in Night Shift is still funny. I dismiss this thread based on not understanding your sense of humor.

This...

I'd be really surprised if anyone would list Airplane! (1980)

Airplane! (1980)

I'll probably be in the minority, but I think except for the airport scene, most of Planes, Trains and Automobiles isn't that funny.

Surely you must be joking.

I'd say any joke that relies on current pop culture as it is immediately dated... i.e. 99% of Shrek.