Up the Bum 

anal sex, and the prelude to an amusing rhyme which kids at school write on each others textbooks to get their friends in trouble:

up the bum, no harm done!

additions:
with a thumb, twice as fun!
with ya mum, watch me cum!

Up the Bum by me old fruity October 1, 2006

Up the BUM 

To take someone from behind

Jazz takes Izzy up the BUM

Up the BUM by Jazz B (+ Mike J) March 25, 2003

Up the Bum 

when michael takes random people (e.g his father) up the bottom

Up the Bum by Anonymous April 1, 2003

Up the Bum 

The ramming of aerodynamic and not so arodynamic objects up the hrmm... anus

Everybody goes to take michael's mum up the bum while he watches in dispair.
Then he decides to go take some tall dark and hansome man up the bum in a dark alleyway, allllll night long. Bless his little gay soul

Up the Bum by a guy with great taste in music June 7, 2003

up the bum no babies

A method of birth control?

up the bum no babies by Minges and all! April 15, 2003

Up the bum, no harm done 

An expression conveying the convenience and lack of danger in conceiving children in Anal Intercourse

Man 1: I didn't want to get her pregnant, so I did her up her rear end!
Man 2: You know what they say: "Up the bum, no harm done!"

Up the bum, no harm done by Albury W Brown May 26, 2017

Up the Bum No Babies

The action of having anal sex to ward off babies.

`meth: Great now I got SR pregnate.
Soul-Reaver: Hm? Up the bum, no babies

Up the Bum No Babies by Cornflake September 23, 2004