A good sense of humor goes a long way in the classroom. My students are in the 17-20 year old range, and I have to keep their attention and confidence for the whole term. When I make a mistake, the best way to deal with it is to be real about it with a bit of humor. Unlike many of my colleagues, I don't need to hide behind a podium because I look the students in the eye and smile from the start. The best way to teach figurative language is by telling jokes, too. For example, yo momma jokes are good for explaining hyperbole.
The funniest thing I saw this week was a video on tv of a pickup truck rolling over five abortion protesters at the same time. I couldn't stop laughing about it all evening.