When I attended NTID, there were a few times I'd heard about and seen Silly Stringed hallways in the dorms. It gets even more impressive when you cover someone else with the stuff.
A friend and I were talking a bit and I had a can of the stuff in my hand, talking in the doorway of the dorm room. One girl walks by, and I give her a short burst of String spray. Next thing we know, she's screaming her head off, trying to brush the stuff off her while running down the hallway. Needless to say, my friend and I were nearly on the floor laughing til her boyfriend comes up and close to me. "Don't you ever do that again" he said.
It could have been worse, but we were too far gone laughing. I was only able to stop briefly til he left before we just fell over laughing again.
Last time we laughed like that, we were watching Brewster's Millions. The baseball game scene where John Candy's catcher character was insulting the batter put us on the floor for the next 5-10 minutes. We had to stop the movie til then.