A Mini Swiss Army Knife. I didn't realize it wasn't allowed. I thought only knives over a certain size were prohibited. Sad thing is that I had probably flown with it a dozen times before anyone caught it.

Once I forgot that I had a can of Red Bull left until I was almost to the security line. I chugged it in about 10 seconds. I don't recommend that. You really don't want to go through security with your eyeballs bulging like that.