I'm not stealing it, and I don't even know who the forget this Karl is or anything about him. I'm not gonna try to put up fliers because the odds are many, many people will want it. I'll just clean it up and sell it to Gamestop or something.
You should put up fliers, especially where you found it. If a person comes calling for it, they should have to answer some questions to prove it's theirs. In this case, what name was on it or the birthday on it.
Of course, you've removed the stickers now, but you should still try to get it back to its owner.
You'd be really annoyed if you'd lost an expensive item and no-one returned it to you, and you'd be really happy if you lost an item and someone returned it to you.