Have you lost any Bitcoins?

Hi. I've always been interested in the question of how many people have lost their private keys and are now kicking their ass. Have you ever lost BTC? If so, how much and what would it be worth now? :D I think this could lead to a nice discussion :)

P.S. I remind you about the guy from bitcointalk who bought two pizzas for 10,000 BTC :)