Activity that is mischievous, stupid, or time-wasting. / Activity that is morally questionable or even mildly illegal.

(dated) A type of close-fitting jacket worn by sailors. / A semiformal lightweight jacket, usually made of nylon, with striped cuffs and neck, similar to an MA-1 flight jacket.

(idiomatic, slang) A mechanic, often with the specific connotation of an automobile mechanic.

(professional wrestling) A move in which a wrestler takes his opponent and flips that person over his head.

to perform a monkey flip

A jungle gym. / A row of bars, found on playgrounds, under which one hangs by the arms and crosses by brachiation (swinging between bars, legs dangling down).

(idiomatic) To act foolishly.

Alternative form of monkeyshine

(zoology, primatology) Any of several small New World monkeys, of the genus Saimiri, that live in Central and South America.

(slang, chiefly sports) A steroid or testosterone abuser.