Who's under the bed sheets?

This is a story told to me from Peter, my brother, and it is about his girlfriend's brother.  This is according to what I remember.

This took place early morning, maybe 6ish I think, at his girlfriends house.  Her brother sleeps in the basement and had just gotten up and went to get something to drink in the kitchen upstairs.  When he came back downstairs, there was someone sitting on his bed with the blankets over their head.  He thought that it was his friend because the night before, his friend had came over to spend the night at his house.  He walked over to his bed and touched the blanket where the head was, and the blanket just falls flat down on the bed as if no one was under it at all.  He got freaked out and ran upstairs to find his friend sleeping on the couch.