Crack up verb – To declare enthusiastic approval of. Funny and crack up are semantically related. In some cases you can use "Funny" instead an adjective "Crack up".
Funny adjective – Causing or intended to cause laughter. Crack up and funny are semantically related. Sometimes you can replace term "Crack up" with "Funny", this adjectives are similar. Nearby Words: funning, funnily
In Snow White and the Seven Dwarfs, originally Dopey made a funny face that ruined the mood of the crying scene and made the test audience crack up, so it was cut.