Green’s Dictionary of Slang

(US teen) in context of an action, incompetently, foolishly.

1960

Baltimore Sun (MD) Sun. Mag. 4 Dec. 9/1: ‘Problem with you [...] is that you’re playing it late. You’re cool like a moose. You hit a boo-boo when you let him know you had the Zorros. Learn to knuckleball’.