also: こけにする
expression, suru verb (irregular)
make a fool of; look down on; treat with contempt
Used when someone treats another person as insignificant, foolish, or not worth taking seriously. Often implies a dismissive or mocking attitude.
彼はいつも私をコケにするような言い方をする。
He always talks in a way that makes a fool of me.
そんなに人をコケにしたら、いつか痛い目を見るよ。
If you look down on people like that, you'll regret it someday.