'Bunking up' involves multiple (at least 2) people sleeping in the same bed and usually involves spooning in some arrangement (preferably the quad-spoon formation). It generally occurs between the hours of 1 am and 3 am after large quantities of alcohol and a long night of pesting
Sometimes the bunk up follows the age old rule of spooning leads to forking - however - it can be completely platonic.
The ideal number for a 'bunk up' is between 2 and 4 - however there have reports of a 5+ people in a spooning arrangements.
Common issues with 'bunking up' include over heating, a uncomfortable sleep and people getting handsey.
Scotty - are we bunking up?
Rob - Let's bunk up - who we going to invite back?
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.
The process of copulation/fornication.
You couldn't get a bunk up in Bangkok mate!
to assist a climber by pushing him/her upwards
"'ere Stephen, g'is a bunk up, I'm nearly over this wall."
having sex with a tampon in place
My husband was bunking up with the roommate last night.
Guy: wow, your mom is so hot.
Other guy: man, that's so bunked up! Don't say those things.