Used in the movie "The Mack"
Literally the Shade Tree that everyone sits under to rest. A guy that stupidly supports and provides wealth for a whore, her family and her bastard children.
Excerpt from the movie "The Mack":
"....Shade Tree N*****r. Your nothin' but a Rest Haven for ho's."
Basically, someone who works on their car by themselves, as a "do-it-yourself" project. He/She often employs jerry-rig techniques to fix his/her automobile. Could also apply to anyone who is a "do-it-yourselfer" in any aspect of life.
"It used to be that under every shade tree there was a mechanic working on their car."