Press button/receive bacon has been my favorite for years...it's hard to think about buttons without saying it out loud. I'd kill to have it on a shirt \m/
One of my favorite movies is Throw Momma from the Train...the first time I saw it, I was laughing through the entire thing, and my friends just kept looking at me weird ¬_¬ I've seen it at least 20 times, and it still makes me laugh every time.
But I think, in my entire life, the one thing that made me laugh the longest was when I saw Shrek 2 at the drive-in with a friend...I thought the movie was kind of a let-down after the first (which isn't the god-send everyone claims anyway), but there's a scene where Shrek and pals are in a disguise at the factory, and he walks past a worker and goes "Working hard, or hardly working?"
I don't even know why, something about the delivery and the situation in general, I just lost it. I'd laugh for a good few minutes, then I'd finally suck it in...and lose it again a few minutes later ;D The laughing fits even continued into the movie afterwards, 50 First Dates. All of a sudden I'd just go "Working hard, or BWA HA HA." and fall over laughing.
Man...good times.
But yeah, getting in trouble for inappropriate laughter sucks =/ From my experience, it seems like girls are more likely to get on my case about it >_<