A man was sitting in a bar and noticed a group of people using sign language. He also noticed that the bartender was using sign language to speak to them.
When the bartender returned to him, the man asked how he had learned to use sign language. The bartender explained that these were regular customers and had taught him to speak in sign. The man thought that was great.
A few minutes later the man noticed that the people in the group were waving their hands around very wildly. The bartender looked over and signed, "Now cut that out! I warned you!" and threw the group out of the bar.
The man asked why he had done that and the bartender said, "If I told them once I told them 100 times - NO SINGING IN THE BAR!"