One at Heathrow a few years ago..
2 aircraft heading to the runway for departure, one German, one Brit.
Tower. 'Lufthansa xxx, clear to line up'
Speedbird. 'Why is that aircraft ahead of us?'
Lufthansa. 'Because we got up early and left our towel on the runway..'
One I've never used myself.... 'Climb like your life depends on it..... because it does!'