when you realized that if somthing cost $12 and you give $22, you get a $10 bill back and don't have to carry around $8 in change... (greatest realization ever)
when you finally got the image just right on the pornos that used to be on viewers choice and you could actually see a titty or two, in negative, but still. Come on, i know its not just me that did this in the early 90's.