Mr Mackey first appeared in South Park in 1997 as the elementary school counselor, voiced by co creator Trey Parker and known for ending sentences with m'kay. Clips of his lectures and investigations were shared for years in compilations and soundboards, and short lines like this one became easy reaction audio. The who did it question fits almost any accusation, so editors keep reusing it for school stories, gaming lobbies and family jokes where someone is clearly guilty but will not admit it.