You're about as useful as a one-legged man at an arse kicking contest.

I'm as poor as a church mouse, that's just had an enormous tax bill on the very day his wife ran off with another mouse, taking all the cheese.

Look, if I'd wanted a lecture on the rights of man, I'd have gone to bed with Martin Luther.

Your services might be as useful as a barbershop on the steps of a guillotine.