"Get Proof" joke

A man went to his lawyer and told him, "My neighbor owes me $500 and he doesn't want to pay up. What should I do?""Do you have any proof?" asked the lawyer."Nope," replied the man."Okay, then write him a letter asking him for the $1000 he owed you," said the lawyer."But it's only $500," replied the man."Precisely. That's what he will reply and we will have the proof we need to nail him."