Some stoned dude walks into the 7-11. He goes up to the man behind the counter and says "got any weed?" He says "no!" So the stoner leaves. The stoner comes back and asks the guy behind the counter "Hey you got any weed?" The man says "No I told you yesterday, we don't sell weed here." So the Stoner leaves again. The stoner walks in the next day and says "Got any weed?" The clerk behind the counter says, "Look you fuckin burnout we don't sell weed here, if you come in here again, I'm goin to nail your fuckin teeth to the floor!!!" So the stoner leaves. He comes in the next day. "You got any nails?" "No", the clerk replies. The stoner looks at him in the eyes and says, "You got any weed?"
I've heard that before, only the stoner was a duck and instead of weed the duck was looking for crackers, and the 7-11 was a bar. So it was completly different but the same idea. It's an awesome joke though