Can I get a joke-explainer?
"To trip up" means "to cause to stumble or make an error". It's also short for triple-up-arrow. Putting a 3^^^3 into an argument often trips up reasoning, and that's the main reason people use that number.
(Apparently this is less intuitive than I thought; MrMind pointed out a third interpretation, which I hadn't thought of before.)
This is a thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. The previous "stupid" questions thread went to over 800 comments in two and a half weeks, so I think it's time for a new one.