“Yo!” said the Dean.

“Yo what?” said Ridcully.

“It’s not a yo what, it’s just a yo,” said the Senior Wrangler, behind him. “It’s a general street greeting and affirmative with convivial military ingroup and masculine bonding-ritual overtones.”

“What? What? Like ‘jolly good’?” said Ridcully.

“I suppose so,” said the Senior Wrangler, reluctantly.

Terry Pratchett (1948-2015) English author

Reaper Man (1991)