back twat 

opposite of front bum ie female anus

back twat by jonny the rocker September 13, 2003

Backtwat 

Like a twat but found between the buttocks.

"MATE I FOCKING RAMMED HER IN THE BACKTWAT AND SHE LOVED IT"

"My backtwat is sore from all that ramming"

"Josh rammed an empty beer bottle up my backtwat and I had to get it removed at A&E"

Backtwat by Tommycopter February 1, 2009