I've heard of this one recently, and I'm not a big fan of jokes, but oh well, let's see...
A panda walks into a tavern and orders some food. After eating the ordered food, the panda grabs out a gun, and then shoots everyone. One of the survivors of the shooting asked the panda, who was in the process of leaving, "Why did you shoot us!?" The panda said, "Read this about pandas." He gave the man a dictionary/encyclopedia. On the entry, it says: Panda. Eats, shoots and leaves.