I recently read a different take on the clichéd line – “He could sell ice to an Inuit*” with “He could sell sawdust to a lumber mill”.
* Politically correct update
I thought, I’d add to the cliché crashing party with examples in two styles, the original – i.e. “Selling someone something they already have” and different – “Selling someone the opposite of what they need”.
1. Sell plastic surgery to Joan Rivers.
2. Sell a cape to Superman.
3. Sell hay to a farmer.
4. Sell wood to a forest.
5. Sell religion to the Pope.
6. Sell underwear to a nudist.
7. Sell rope to a free climber.
8. Sell a two-wheeled bike to a unicyclist.
9. Sell crutches to an Olympic sprinter.
10. Sell a cage to a lion.
Bonus. Sell atheism to a doorstep Jehovah.