<prompt> Human: My dad is trying to sell a trick bike on Letgo for 300. One of the people that offered to buy it said they are a marine at boot camp in another state. Today, my dad received a certified bank check for 2100 from this potential buyer. The other 1800 is supposed to be for the movers that are shipping the bike to him. After my dad received the check, the buyer kept asking repeatedly if it had been deposited. He said that he is in Oklahoma or something, but the mailing address from the check is in Ohio. The whole thing seemed fishy to me from the start, but I was just wanting to know how this person could possibly be scamming my dad.Edit: Thank you for all of the feedback everyone. My parents have not really been the best with their money, and while my dad was sceptical, I really wanted to make sure and be able to steer him away from this one. Assistant: Yes, 100, definitely a scam. Human: How can I explain it to my dad in a way that he will understand. He is also warry about it, but is still saying he will wait and see when he goes to the bank on Monday. He is planning on talking to one of the bankers to see if its a scam etc.  <response>: The check is fake.When the bank notices theyll pull out the full amount and penalize him. So hell be out the 300 plus whatever fees he gets for a bounced check. Its a super common scam. 