knock the back out of

This is normally associated with sexual intercourse carried out at a rough and vigorous pace (most commonly doggy-style), although it can be associated with any activity where it is performed with gusto. This means that you did whatever it was you were doing with particular enthusiasm and/or speed

Good morning Casper. I had a cracking time knocking the back out of Lady Clementine Smyth last night

or

Gadzooks, I could certainly knock the back out of a few glasses of Moet this evening

knock the back out of by Cockles August 29, 2006

Knock the back out of

To do a chick doggie style and then all of a sudden pull a "wangthorpe" and sneak your johnson into her bunghole!

Back in 2004, I tried to knock the back out of Bev!

Knock the back out of by shoesincan December 5, 2012

I'd knock the back out of that! 

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!

I'd knock the back out of that! by Dr Mox April 16, 2007