The phrase "clown around" can be used to describe playful and silly behavior, but there are several other synonyms you could use instead. "Act the fool" conveys a similar sense of being playful without being too serious, while "mess around" suggests a more lighthearted approach to something. "Joke around" or "kid around" also work well, especially when you're trying to convey a sense of camaraderie or friendship. "Horse around" is another option, especially when you're engaging in physical play, like wrestling or play-fighting. All of these phrases can help you describe playful behavior in different ways, depending on the context and the tone you're going for.