Calvin in Liquid Form is a minor recurring alter ego of Calvin's. He appeared in three Sunday strips as a body of water that resulted from Calvin melting or otherwise losing solid integrity. The reasons for which he was liquified were never the same, though.
Drinking too muchCalvin's liquid form first appeared as the result of Calvin disrupting his internal balance of solid and liquid; drinking a glass of water made his water content reach 90%, dissolving Calvin's solids. Although Calvin claimed that "the human body is 80% water", this figure is only true for infants, and the percentage would be much lower at Calvin's current age.
Despite having no solid mass, Calvin's liquid alter ego was still able to reason and even carry an expression. It was analogous to Calvin being unable to "hold it in" during a car trip after drinking too much.