After you buy it, you drop it. Then you use it. What is it?
[Yes, you drop it deliberately.]
Tanya has it, but I'll consider a better answer that I didn't anticipate if one is posted. The problem with all the balls and the yo-yo is that you are already using them when you drop them. I agree that you break an egg before using it, but I've never dropped one just to break it.
When I was a kid I used to break open coconuts by hurling them against the pavement, but dropping won't do it.
Thanks for all the answers.