clown around, also UK: clown aboutvi phrasalphrasal verb, intransitive: Verb with adverb(s) or preposition(s), having special meaning and not taking direct object--for example, "make up" [=reconcile]: "After they fought, they made up."
informal (play the fool, behave in a silly way)
扮小丑 bàn xiǎo chǒu
One can never take him seriously; he's always clowning around.