Your Favorite LOL Scene(s) in Any Comedy-Type Film(s) ...

Oh yeah, Who's Harry Crumb? might not be on the same level as Planes, Trains & Automobiles "quality" wise, but it is still a very funny, silly/goofy late 80s John Candy vehicle that comes with some great laughs, and while some of the jokes might not be seen as, well "appropriate" by todays "standards", I really enjoyed how he comes off as a big mix of The Pink Panther (Peter Seller), Fletch (Chevy Chase) and the Ace Ventura (Jim Carrey) films by portraying a very clumsy but lovable private detective.
Two of my favorite scenes from that John Candy films is when he goes undercover as Vijay from Bombay which features a small guest part by Joe Flaherty as the doorman and then of course the hilarious I am Deszu Djizlas. These scenes are so silly and cheesy but I cannot stop laughing, "MOVE, MOVE DENNIS!", "TOO FOOOOFY!", and my favorite: "Maybe your eyes are playing tricks on me".
Now that is how you bury the hatchet, when dealing with a creep such as BUG, the Uncle Buck way that is. 
The clown scene in Uncle Buck is comedy gold.
I had absolutely no idea that it was Mike Starr who was Pootah, the clown when I first saw it. But over the years I noticed that he has done a lot of great and very funny small parts in many comedy films, and while he might often strikes you as a scary looking guy, but from every interviews and behind the scenes I have seen him in, he has always come off as a really standup and kind guy.
And he is one of those actors who could have ended up just doing the same "villain/henchman" things in mobsters/gangster films, all the time but instead he is a bit of a "chameleon as he has proven over and over how funny he can be against some of the biggest stars in the movie business:

One of the funniest scenes I have seen of Mike is of course his classic character, The Gasman from Dumb and Dumber (1994),  and to have a guy like Jim Carrey back in his prime days, it must have been pretty damn hard trying to hold a serious/straight face/mask when doing scenes like this:

"Radio! Who needs the radio!? Ready Harry? MOCK! YEAH! ING! YEAH! BIRD! YEAH! YEAH! YEAH!"