What if I receive fake money? Can I sue?

As you can see from your description, the other party did have doubts when collecting money.

2

Since the other party has accepted it, the other party has no right to ask you to exchange 100 yuan from the moral or legal point of view. Because when he accepts it, the business between you is completed and legal.

three

Isn't there even a slogan in the bank that says, "You are not responsible for the coin when it comes out?" It can be seen that it is not easy to find it by counting it yourself.

four

If the other party calls the police or even goes to court, you have nothing to worry about. According to the law of who advocates who gives evidence, the other party must be able to show that the counterfeit money he said was indeed given by you, and I'm afraid he can't produce this evidence either. Then he will have to bear the consequences of losing the case.

five

Besides, it takes so long from the end of the transaction until he sends you a message, and he has enough time to exchange, which is wrong for the other party.

six

Is it your long-term customer who delivers takeout? How is their company?

In addition, you can inquire about the other person's character. You said that you were not sure if what you gave was counterfeit money. On the other hand, if the other person's character is really good, or you have any difficulties, you can also give him 100.