A stoner walks into a gas station and asks the dude at the counter, "Got any weed?" The man politely replied, "Um, no sir. We do not sell marijuana here." So he left.
The same guy comes back the next day and says, "Got any weed?" The man behind the counter, although slightly annoyed, patiently replied, "No sir. We don't sell marijuana." So the man went home.

He goes once again to the gas station. And again, he says to the guy working there, "Got any weed?" By this time the other dude was pissed. He yells, "You freakin' refer-lovin', pot-head burn-out! I told you, we don't sell that crap here! If you ever come back in here asking for that filthy crap again, I'll nail your freaking feet to the floor. Got it? Now beat it before I call the cops." So the stoner left.

The next day he went back to the same old place with a dopey smile on his face. He went to the cashier and said, "Got any nails?" The man hesitated, then replied, "um, no. . . sir, we don't sell nails here." The stoner grinned. "Got any weed?"