As a kid, I used to have a lemonade stand.

As a kid, I used to have a lemonade stand. The sign said, "All you can
drink for a dime." So some kid would come up, plunk down the dime, drink a
glass, and then say, "Refill it." I'd say, "That'll be another dime." "How
come? Your sign says--" "Well, you had a glass, didn't you?" "Yeah." "And
that's all you can drink for a dime."
-- Flip Wilson