Okay kiddo, so sometimes when there is a competition or a game, there is a prize for the winner, right? But sometimes, just for fun, there is also a prize for the person who didn't win, and that's called the booby prize.
Now, the booby prize is not really a prize that you'd want to win, because it's usually something silly or not very useful. It's kind of like a joke prize, to make everyone laugh and to make sure that the person who didn't win doesn't feel too bad.
For example, let's say we are having a race at a party, and you come in last place. Don't worry, you can still get the booby prize! It might be something like a paper crown or a silly hat, or even just a big hug from everyone else. It's a way to say, "Hey, we know you didn't win, but we still appreciate you playing and having fun with us."
So, that's the booby prize, a silly prize for the person who didn't win. But remember, winning isn't everything, it's all about having fun and trying your best.