Gas

My kids are at an age where passing gas in front of others is funny. My daughter is very quick to say, "excuse me" before she falls over laughing. My son just thinks it is the funniest thing ever if he has gas while showing me his latest ninja moves.
I don't know at what age this changes, but apparently by the age of 9 or 10, it isn't cool to do this in front of the opposite sex.
We were at my son's karate class today and an older boy, waiting in the wings for the next class, was messing around with some karate moves. He was apparently trying to impress his classmate, a girl, who was standing next to him. Amanda and I were sitting next to them when we heard it... the unmistakable fart. The boy quickly moved to the opposite wall. The girl then went to stand next to him and said, "you stink." He was quick to reply that someone had farted, but it wasn't him. He went on and on about this for about 2 minutes... "someone farted, but it wasn't me."
I was very tempted to help him out and say, "Oh, sorry, I had Taco Bell for lunch," but I didn't. Instead I watched as the red-faced boy went outside to wait for his class to begin.