Shooting guard Puns

Me: Sure, tell me one son. My Son: Did you know that Lincoln had a guard with him at the theater where he was shot, but that the guard left to go across the street to have a drink and that's why Lincoln wasn't guarded when he was shot? Me: No, son, I had no idea. My Son: But that's not all. It was the same bar that John Wilkes Booth was waiting in before going to kill the president. Me: So did they see each other? My Son: I'm not sure dad. I'm thinking Booth might have been waiting to see if he would come in before he went over to shoot Lincoln. Me: I wonder if the guard came in, and Booth ask him if he could buy him a shot?!?!? My Son: audibly smacks head