I used to work with a one-armed fella.
He was once trying to lift something rather heavy and I, without even pausing to think about what I was saying, asked him if he needed a hand.

Fortunately, he'd been that way from birth and had grown up with a prosthetic arm on his other side, so had developed a pretty decent sense of humour about the whole thing. So much so that one of his strategies for averting booze-fuelled aggro at certain pubs was to stub out his cigarette on his (fake) hand.
( flake has nothing against your right leg, Sat 14 May 2011, 1:29, Reply)