Cartoon impact sound, 4 letters
Cartoon knock-on-the-head sound, 4 letters
Comic strip sound effect, 4 letters
Knock on the noggin, 4 letters
Knock on the noodle, 4 letters
Noggin-knocking sound, 4 letters
Peanuts sound effect, 4 letters
Strike on the head, in cartoons, 4 letters
Three Stooges sound effect, 4 letters
Funny hitting sounds, 5 letters