Maybe she considered you as a person to be more witty,and comical with.Usually people who have good friendships play around by saying stuff like that. You should have replied, "Wake up,or I'll chop YOUR head off." or something like that. or if she was'ent kidding,play the friend sympathy card, "Whats wrong with you?You sound like your in a bad mood." or maybe " I see YOU had alot of sleep last night"