A guy walks into a grocery store and asks a worker, "Do you have any grapes?".

The worker replies, "Sorry, we're all out". And the guy walks away.

The next day, the same person comes in again and asks the same guy, "Do you have any grapes?".

"I already told you, we are all out." replies the worker.

Once again, he walks into the store the next day and asks the worker, "Do you have any grapes?".

"NO!" shouts the worker, "IF YOU COME BACK AND ASK ME THAT ONE MORE TIME, I WILL SHOOT YOU IN THE HEAD WITH MY OWN GUN!".

The following day, the guy comes into the store and asks, "Do you have any guns?" to the worker.

"No," says the worker.

"Do you have any grapes?"