To have sex with a women doggy style. This is commonly mistaken for anal, however the penis still does the thing with the vagina except the man is standing behind the female. Hence hit it from the back.
"You're weak on top, you cant ride like a stallion....hit it from the back, hit it from the back" "Hit it from the back" by Mobb Deep off of their debut album Juvenile Hell
A couple of words men learned from watching dogs have sex. Women get this when they have a nice body but fucked up face, so that we don't have to see their face...........