To tease or make fun of someone in a playful or mocking way; to poke fun at someone (colloquial).
彼は妹の服装をいつもちゃかしてばかりいる。
He is always teasing his younger sister about her clothes.
冗談のつもりでちゃかしたら、相手が怒ってしまった。
I teased them as a joke, but they got angry.
みんなで先輩をちゃかして場を和ませた。
We all teased our senior to lighten the mood.