Excessive heatThe alter ego later reappeared when, on a hot summer day, Calvin melted into a puddle on the sidewalk outside his house. The puddle evaporated into a small cloud, which then rained down a reconstituted, solid (but completely naked) Calvin. According to Calvin's mother, this liquid form had appeared at least twice.
Unlike in its first appearance, the liquid form was here a melted version of a solid Calvin. Even so, it appeared as a clear, runny water puddle instead of a body-colored viscous fluid.