Three men sat in the pub, arguing over what they think is the fastest thing in the world.

First man says 'I think it's electricity. You flick a switch and it's there instantly and you can get rid of it just as quick'.

Second man replies, 'Nah, I think it's human speech because you can control that'.

There's a slight pause while the third man takes a sip from his pint

'You know', he starts, 'you're both wrong. Fastest thing in the world is diarrhoea.' His friends look at each other, slightly confused.

'Why's that then?' asks one

He replies 'because by the time you've switched the light on and called for help, you've already **** yourself'.