A man is having a pee in a pub toilet and next to him is a man standing at the urinal but without any arms.  So feeling obliged he says, "Can you manage?"

The man says "Would you mind pulling my cock out, pointing it while I pee and then giving it a shake?"

He feels very awkward at having to do this but does as asked. As he's holding the mans cock he notices it's covered with scabs and all kinds of scars, he gives it a shake, puts it back in and says "Do you mind if I ask what's wrong with your cock?"

At which the bloke pulls his arms out from under his coat and says, "Fuck knows, but I'm not touching it!"