One day, a duck walks into a bar. He goes up to the bartender, sits down on a stool and says, "Got any grapes?" The bartender looks at the duck and says, "No, Duck, this is a bar. We have no grapes." Without saying anything else, the duck walks out.
The next day, the duck returns, sits down at the same stool, and again asks the bartender, "Got any grapes?" A little irritated now, the bartender replies, "Duck, I told you once before, this is not a grocery store. WE HAVE NO GRAPES." The duck walks out.
However, the next day the duck walks in and asks for a third time. "Got any grapes?" The bartender is really angry now and yells, "I swear to you, Duck if you ask that one more time I'm going to nail your beak to the counter!" The duck walks out.
The fourth day, the duck enters the bar again, and asks the bartender, "Got any nails?" The bartender, his temper pushed to the max, slams his fist on the bar. "NO DUCK! This is not a hardware store, it is a BAR!" The duck looks at him smiling and says, "Good! Got any grapes?"