The best sleepover I remember was for a cousin's birthday. I think we were all about 12. My cousin had a tendency to act like she was queen of the world. Some of us got pissed off at her and she, along with two of her "more mature" friends, were pissed at us. They went to sleep while the rest of us stayed up having fun until some wee hour of the morning. We played Bloody Mary, Light as a Feather, tried having a seance, had a Kool-Aid chugging contest, and made fun of my cousin when she started talking in her sleep. It was a blast.