Winner's curse is a fancy term that talks about when you're bidding on something, kind of like a toy or a game at a fair, and you end up winning it, but then you realize that you paid too much money for it.
It's like when you're playing a game with your friends, and everybody wants to win, and everybody keeps bidding higher and higher to try to win. But the one who wins ends up paying more than what the thing is actually worth, and they realize it later. It makes them feel bad because they won, but they paid too much for it.
So, the winner's curse is when you win something, but you end up overpaying for it. It's not a very fun feeling, and it's important to remember that sometimes, it's better to just let someone else win instead of getting caught up in the competition.