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

Any member of the clade Simiiformes not also of the clade Hominoidea containing humans and apes, from which they are usually, but not universally, distinguished by smaller size, a tail, and cheek pouches.

(idiomatic, of the weather) Very cold.

(vulgar) Energetic but useless action, or a person engaged in such action.

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

to perform a monkey flip

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

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) Often preceded by well: expressing complete surprise or disbelief.

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