Quisling

Okay, so imagine that you and your friends are playing a game where you're all on the same team. Let's say you're playing a pretend game where you're pirates, trying to find treasure. But then, one of your friends decides to betray you and join the other team. This friend is a quisling.

A quisling is a word that means someone who betrays their friends or country by working with the enemy. It comes from the name of a man named Vidkun Quisling, who helped the Nazis when they invaded Norway during World War II.

So basically, a quisling is someone who turns against their friends or country and helps their enemies instead. It's not a nice thing to do, and it can be very harmful to the people who trusted you.