Joha sells sold anti-flea powder to a man. "The powder didn't work," the man complains. "You used it wrong," says Joha. "You can't just sprinkle it. You have to catch the flea, open its mouth, and put the powder down its throat." "I might as well squash them," says the man. "Well, sure; that works too," says Joha.
Notes: Same story told about Nasruddin and rat poison in Ohebsion.