Calvin's Allowance is when Calvin's dad gives him money, but is unsuccessful, because Calvin always thinks that after he's told he gets an allowance, the world is his.
In one strip, Calvin has spent his whole allowance and wants a grenade launcher. He goes to his mom and asks when it will be Christmas, and she answers, "Not for a long time." He then asks when his birthday is, and she again says, "Not for a long time.". Finally, he asks when his allowance is, and she says, "You spent it already." Calvin then sells the car with a sale stand. Although we really don't know the first time it happened, Calvin's dad mentions that "He blew it again, dear", implying that he has sold the car before.