<prompt> Human: I advertised something for sale for 900. Guy shows up, likes the item and talks me down to 800 on the condition that hell bring someone to help him move it next week its a very heavy item. He was saying something about needing to charge this to his business and he could do that a number of ways, including writing me a check or two checks. I said cash.He gave me 200 in cash as earnest money and I wrote him a receipt detailing the fact that it was 200 down on a 800 purchase. He left. I didnt think to keep a copy of that receipt.Today I got an email asking about a feature. When I said that feature wasnt there, he said that was a dealbreaker. But, because a deal is a deal, I could keep 100 and could I send him a check for the other 100.I feel morally obligated to give him the full 200 back. But I feel a little nervous about the charge to business and check stuff. This isnt some complicated scheme, right? And I could just mail him the same 100 bills he gave me and I couldnt possibly be out any money.I have most of this in email, except for what we talked about in person and of course the receipt.It just now occurred to me that the 200 cash could be counterfeit. It has hologram strips, so I guess Im OK?EDIT: Just had a bank check them--they are OK. I think this guy is just kind of an airhead and made a mistake.  <response>: Anytime I feel sketchy on craigslist I have found a nearly fool-proof way to put my nerves at ease, or completely justify them because the other party will stop all contact: Tell him to meet you at the local police station parking lot to complete the transactionAnyone who is sincere will have no issue with this. Anyone who takes issue with this is probably not someone I want to be doing business with. 