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 spitting each other in the chin. Have you ever lost BTC? If so, how much more and what would be the value now? : D I think a nice discussion could result from this :)

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