When you act goofy with your friends, that's clowning. Putting on stage makeup, a purple wig, and a red nose before performing in a circus is another kind of clowning.
Use the term clowning for the art and practice of being a clown, a performer who excels at gags and pratfalls. Professional clowning involves learning things like pantomime, juggling, and even acrobatics. Circus clowning provides the comic relief between high wire acts and other feats of daring. A more casual kind of clowning is when you simply act silly: "Stop clowning and pay attention to the teacher!"