An unlicensed or on-the-side mechanic that you go to when you can't afford to go to a real mechanic. Often used when the job is simple, or you no longer want to dump money into your very old car.
Can also be applied to a halfway knowledgable person in any field (ie: computer repairs, home repairs, gender reassignment)
"I took my car to this grease monkey I know and he screwed up my tranny. That'll teach me to stop being cheap."
Someone who deliberately does not wash their hair reguarly and is regarded by others as a greasy skett. Hair smells and dandruff flakes are apparent they are not pleasent to look at.
Emma Staunton
"Go grease lightning"
"You' ve got enough grease on top to open up a chip shop!!"
"Err have you seen that Grease Monkey over there!? She wants to go get that hair of hers checked out by the Grease Police!"
Worker #1: She got the biggest ass licking in the world in the weekly newsletter.
Worker #2: She must be giving the boss greasemonkeys in the lactation room.