shenanigans
Playful, sneaky mischief or tricks that are usually harmless.
Shenanigans are playful tricks, mischief, or sneaky behavior that's usually harmless but definitely up to something. When your friends are giggling in the corner and suddenly go quiet when you walk by, they're probably up to some shenanigans. When your little brother hides your homework right before you leave for school, that's shenanigans too.
The word has a lighthearted, playful feeling to it. Shenanigans might be annoying (like someone hiding all the erasers in the classroom), but they're rarely mean-spirited or seriously harmful. There's usually a sense of fun involved, even if you're on the receiving end.
Sometimes people use shenanigans to describe behavior that's slightly dishonest or tricky, like when someone tries to bend the rules without quite breaking them. A politician might accuse opponents of political shenanigans when they use technical loopholes to get their way. A teacher might say “no shenanigans” before a substitute arrives, meaning no taking advantage of the situation.
The word itself sounds fun to say, which fits perfectly with what it means. When someone exclaims, “What kind of shenanigans are you two up to?” they usually know something interesting is happening, even if they're not sure exactly what.