Definitions by sir david attenborough the 2nd

monkey rubber 

A perverted sexual act, where the individual masturbates whilst watching animals shagging.

This can be done in a zoo
or whilst at home maybe watching porn off the animal variety.

number 1: "Did you hear about Dave?"

number 2: "Yeah i know turns out he's a monkey rubber."

monkey rubber by sir david attenborough the 2nd January 10, 2008