Green’s Dictionary of Slang

(US) to lose control, to act in a wild manner.

1937		R. Johnson ‘Stop Breaking Down’ 🎵 You Saturday night women, you love to ape and clown.
1949		H. Miller Sexus (1969) 72: The more he grinned, the more he clowned and aped it.
1967–8		Baker et al. CUSS 71: Ape out Go wild.