A skydiver jumps out of a plane, unfortunately his parachute fails to open. As he plummets to earth he sees a man hurtling up towards him. As they pass he calls out 'do you know anything about parachutes?' The fellow going up shouts 'sorry, no, do you know anything about gas cookers?'
So I was working on a building site and the delivery driver said, 'Why won't you sign for these elevators?' I said 'I'm not allowed to accept lifts off strangers'.