Joe is walking around town when he sees a bar with a sign advertising "All the Beer You Can Drink for $1!"
Joe thinks that's a great deal so he goes in, sits down, hands the bartender a dollar, and asks for a beer.
"Sure, right away" says Mark, the bartender as he pulls out a tiny shot glass and fills it up halfway.
Joe is stunned. "What the hell is this?" he asks.
"That's all the beer you can drink for $1."