To fuck someone so good, they can't walk for a couple of days. Hence their back is blown out.
Boy: Damn, girl, I can blow your back out
Girl: Um, I don't think so, I have a soccer game in the morning and I'd actually like to walk.
by BritneyLee09 October 19, 2008
Get the Blow your back out mug.
To engage in sexual activity, usually in what is often referred to as "doggy-style," in a somewhat violent manner as to cause much volume from your victim, but much pleasure for both parties.
She screamed aloud as she lost her hip control while I was beating her back out
by Mr. P March 1, 2004
Get the beating her back out mug.
when you do it doggystyle and she cant walk the next day or two
I'll blow her back out
by Jamerz November 26, 2003
Get the blow her back out mug.
Said about a sexually appealing woman, with whom you would be very eager to have sex.

To explain the metaphor: you may be a little too vigorous, and push your penis all the way through her, hence, knocking the back out of her... Obviously not physically possible, but a good, although rather crude, metaphor
Guy A: Phwoar, Check her out, what a stunner!
Guy B: God yeah, I'd knock the back out of that!
by Dr Mox April 7, 2007
Get the I'd knock the back out of that! mug.
(V) the act of having sex in the position in which the receiving partner is laying down with back arched up, and the giving partner is entering from the posterior. (See also "face down, ass up.")
Damn, I don't care how much we been arguin, just blow my back out tonight.
by Burdenofproof July 27, 2017
Get the blow my back out mug.