look up any word, like darude - sandstorm:
 
1.
the back fanny is slang for a womans anus..
she is gorgeous,i'd like to make love to her back fanny all night long,
our american friends should be aware in the uk a fanny = pussy/vagina
by dave November 25, 2004
 
2.
The backfanny is the slot that forms in the middle of an overweight person's back when they wear clothes that are too tight for them. It is called this because it resembles the vagina , which is also known in the UK as a " fanny " .
My Auntie Nellie is sixty five so naturally she's carrying a few pounds more than she did in her prime . How do I tell her that she sports a backfanny when she squeezes herself into that little yellow Summer dress ?
by Dr Elephantus January 04, 2011