sign

I have seen people use sign language before. I have seen people talk to themselves before. But it is the first time I saw somebody talk to themselves with sign language. I really wanted to know what they were saying. What is so important they have to sign it out? What is the sign for sticking it your tongue? I have a need to know. It seemed different watching this man sign to himself. At first I thought he was talking to the bus driver. But no the bus driver can sign and drive the bus at the same time. But the guy was fully absorbed in doing his sign language. What is the sign for fuck you? How about shut the fuck up? He just kept on going for more than a half an hour. Was some imaginary person signing back to him. But it was non stop. So he did not let the other person sign back. Good thing he has energy to keep signing. It tired me out just watching.