look up any word, like donkey punch:
 
1.
sexual intercourse
I had a lovely bunk up with Britney last night.
by Dunky Oggins October 17, 2003
 
2.
The process of copulation/fornication.
You couldn't get a bunk up in Bangkok mate!
by Robbo_69 May 20, 2008
 
3.
to sleep in the same bed with someone (not just in the same room).

British usage.
Although Sam only has a single bed, he lusts to bunk up with seb every night.

When Tom met that hot piece, they hooked up, went boozing, and decided to bunk up all weekend.
by anglophile-4u November 28, 2009
 
4.
to assist a climber by pushing him/her upwards
"'ere Stephen, g'is a bunk up, I'm nearly over this wall."
by theWestHamfan October 27, 2003