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