'What's that stuff they put in ships to keep them from going all over the place?' 'What? Oh … ballast?'… — Kingsley Amis

'What's that stuff they put in ships to keep them from going all over the place?'

'What? Oh … ballast?'

'That's right. People's sex drives are like ballast, they keep them steady. It sounds wrong, but they do.'

p. 273Source: Wikiquote · CC BY-SA 4.0