I would like to cross a Bonbo Pygmy Chimpanzee with a full size Silver Back Gorilla.
Why?
Well the Pygmies Chimps greet each other in by having sex. Strange as it may seem they fuck like mad in the morning when the see each other. Even the boys get boned by the men.
I think it would be exceedingly funny to cross a fuck of silver back gorilla so that it inherits the fucking trait and then runs rampant through it's tribe and any populated areas it comes across.