expression, godan verb (-mu)
Idiomatic expression meaning to stick one's nose into other people's affairs, often uninvited.
人の会話に嘴を挟むのは失礼だ。
It's rude to butt into other people's conversations.
彼はいつも他人の問題に嘴を挟みたがる。
He always wants to meddle in other people's problems.