Calvin's sale stands are a running gag in which Calvin sets up a booth (usually made from a cardboard box) to sell some product, much in the same way as many children run lemonade stands. Calvin has used many different ideas over the years to try to earn money, but they were all unsuccessful.
InsuranceThis booth retailed insurance at 50¢ apiece. When Susie Derkins made light of it, asking who would buy insurance from him, Calvin shot windows to break them and get some sales
Family CarCalvin, upon realizing that he lacked money, put up the family car for sale. The price was unspecified, but said to be low, and certainly less than the car's value given Calvin's nebulous conception of money and the economy.
Calvin's Curative Elixir and Pitcher of PlagueCalvin presented a solution called "Calvin's Curative Elixir" to Hobbes. However, the latter argued that it was not a curative elixir of any kind, observing that it was just water from the drainage ditch that had leaves in it. Calvin tried to convince Hobbes to let him sell it by saying that it was "fortified with chlorophyll", but Hobbes managed to convince him to change the name, and soon he was selling "Pitcher of Plague: Calvin's Debilitating Disease Drink" and charging a dollar not to have any.
LemonadeCalvin has put up two lemonade stands over the years. The first time he sold it for five dollars a glass—during winter. He claimed that it had "all-natural refrigeration", which albeit true was no selling point. Another time, he was selling a single glass for an outrageous $15, and his concoction was really just a lemon dropped in a pitcher of unsantitary sludge. Susie Derkins tried to tell Calvin about this, while Calvin attempted to justify the product and pricing through economical phenomena.
Great IdeasCalvin once sold great ideas (at first at $1 each, later reduced to 25 cents). Only Calvin's mother bought one, and the idea Calvin gave her was "Buy some more!". Susie and Hobbes came across the stand, but did not transact, however, after Calvin insulted Susie by saying "Yeah, well go soak your head!", Calvin yells "Hey, that'll be one dollar!"
Suicide DrinkIn one panel of a Sunday strip showing a summer day for Calvin and Hobbes, the two are shown sitting at the box with a pitcher filled with sludge, much like with the Pitcher of Plague. The box read "Suicide Drink 25 cents". There was no dialog in this strip. As it lasted only a fraction of Calvin's day, the business must have been short-lived.
A swift kick in the buttThis was Calvin's least successful business. He didn't sell one, and seemed fairly surprised that it wasn't successful, since he thought everyone he knew needed one.
Bill Watterson featured this strip in the Tenth Anniversary Collection, commenting "People will pay for what they want, but not for what they need."