A person who works on cars a lot is called a grease monkey because your hands get full of grease. Never thought it was racist because the only people I ever knew called that were white, so I didn't make the connection people make with Monkey being a slur against brown people. Also didn't think it was a put down on blue collar workers (of any race) because those were the only people I knew. It was just descriptive. It could have situational racial or economic negative connotations. Example: some wealthy person tries to put down any person working on their car by calling them a Grease Monkey in a derogatory way...most mechanics take pride in their work and themselves, so that would be confusing, and really only prove the rich guy was a pompous ass who doesn't know how to fix his own car.
My Dad and his brothers were grease monkeys, so I learned how to fix my own car.
Flange monkey refers to anyone who loves the flange. ie, someone who likes to look at, touch, lick, or fuck the female vagina.
Usually used as a lighthearted insult
"Oi oiflange monkey! Who's pussy are you lickin tonight?"