A policeman is driving past a roadside apple stand when he notices the sign: “Apple seeds, guaranteed to make you smarter, $20 per seed.”
He pulls over and informs the vendor that it is fraud and false advertising to make absurd claims like this.
“No, no, no,” the vendor tells the cop, “my apples are a special variety. A scientific miracle. Buy just one seed, eat it, and you will notice an increase in intelligence. If not, I promise to refund your 20 dollars.”
“Alright,” says the cop. “But, if this doesn’t work, I’m shutting your operation down.” He hands over a 20 dollar bill, takes the seed, chews it up, and waits for it to kick in.
After a few moments, he says, “You know, even if you’re not lying, I could have bought a whole bag of your apples and had enough seeds to last me months.”
“Ah, yes!” says the vendor. “It’s working already!”