back Share definition Flag a back is a very useful part on the male human body which is very good for scratching up during sex while you have multiple orgasms. sid: dude, my girl fucked me back up ricky: thats awesome sid: yeah, that means i did good. back by mandythestoner October 3, 2004 0 0 Get merch Get the back mug. Buy Now — $32.95 See more merch