I get piñatas, but there is an extreme version of this that I find just too much. Not sure in other places, but in Spain there is a kind of fair stall where children use a plastic fishing rod with a magnet or hook to catch some plastic ducks with the corresponding magnet or hook. The ducks have some points and give you rewards, but the payoff is terrible - maybe you spend €10 and you get a gift that you could buy for €2 at the neighborhood shops. And the fun part with the fishing lasts like 20 seconds, no more, and it's individual, there isn't even a competition or anything, no time limit, etc. Just catch three ducks and see how many points they give you.

My 7-year-old son (who by the way loves math) always wants to go there. I can't help but explain that the payoff is horrendous from any point of view, and he understands and doesn't argue against it, but he still insists. Sometimes I convince him by offering alternatives, but sometimes I have to cave because he seems to like it so much. But man, spending euros on that stings, I have the feeling that the people who run the stall must be laughing at all the suckers who fall into the trap.