A girl that is involved with another man, she is taken, off the market, unavailable.
John: Hey dude, check that bird out at the bar in the purple dress
Dan: Yer i know mate she is hot
John: I'll see if she wants a drink
Dan: Nahh mate shes a backed up woman (or just backed up)
John: For fucks sake!
uncommon english slang use for someone who has been mentaly aroused by drugs which have, therefore led him to a 'gormful' life in which things appear slower and stranger to the person in question. Furthermore, the person deemed to have done a keffen or branded a Keffen seem to have thrown common scence out of a 9 story window to which it has been demoralised to a common toad. Simple things seem a challenge and more intermidiate actions seem frightful or impossible.
1)"mate thats your Television not the toilet" 2)"Fuck off" 1)"You my friend are a keffen"
1)"im elergic to nuts but i thought that they would tell me" 2)"You have just done a keffen mate."