Anyone who has a very low intelligence and doesn't completely know how to pronounce his/her R's and L's. This individual may very well be an asshat or ass monkey. He/she usually will have a false sense of coolness and manliness. The individual typically has a terrible lisp.
Man 1:"Hey man, did you just see that ass monkey walk by?"
Man 2:"Dude thats a Gilstrap. Its not his fault. He was born that way."