The Bed Cover Monster was the sheets on Calvin's bed. It appeared as a monster in a single weekday strip and in a single Sunday strip. Calvin got out of bed, however, the sheets grabbed him and pulled him into its "mouth." This is analogous to Calvin trying to get out of bed, as his mother said to him, "For the last time, get out of bed! We're going to be late!". In the Sunday strip, it had a much smaller role. It simply picked up Calvin, and literally flung him down the stairs.