Other forms: japeries
Do you love silly practical jokes? Then you're a fan of japery, the act of clowning or pranking.
You could also call it "buffoonery," "merriment," or even "monkey business," but japery is a great, old-fashioned term for goofing around and generally acting like a clown. Your sister's japery might include things like putting whoopie cushions on people's chairs, while you may be more fond of japery in the context of clowns at the circus.