A term that refers to a man's penis with the added reputation of being in the ass, hands, pussy, or mouths of a female slut(s). Due to it's popularity, one's "slut monkey" is frequented by sluts, and is never at rest.
"Trust me Jane, there is nothing to fear from my slut monkey - it's friendly!...", said John. Believing his words, Jane started to direct it into her already juiced cunt.