Phrase that indicates sudden sexual pleasure or orgasm (male or female). Or if you want, it could mean absolutely nothing, only that you wanted to say "Ohhh, monkey." If used during sex, the phrase is then emphasized. "OHH, MONKEY!" *Must be said with an "oh face" and a voice similar to one having an orgasm.*
"Hey, check out that girl over there. She's practically naked."
"Ohh, monkey." (suddenly jizzes on face)