Hijinks stereotypically ensue.
Was I just super nerdy and didn't actually do anything interesting when my friends stayed over for the night? Seriously, in stories everybody seems to get into a lot of trouble. For me, when my friends came over we just hung out until it was time for bed and then we actually went to sleep. We played video games, and that kind of thing. Although video games are probably against the rules in the Bears' house.
This is just two people; it's not a party. They're just sibling friends of Brother and Sister. "We're supposed to get into trouble! Let's get into some super-stereotypical trouble right now!" The trouble that they get into is just so stereotypical, it's not believable. They tell a scary story, one of the girls gets upset and yells, then they go out in the kitchen and make snacks, and then they go into the bathroom where the girls put on Mama's lipstick and the boys put on Papa's shaving cream. It's so stereotypical, it even follows gender stereotypes. Why don't the boys put on lipstick? How come you never read that in kids' stories? Not terribly interesting. No real point.
Lizzie and Barry Bruin spend the night at the Bears' house. They put on a magic show, then somebody falls over and Mama and Papa tell them it's time for bed. They go to bed, but nobody's tired. Brother tells a scary story. Lizzie screams. They get into the snacks, they get into the makeup, and then the next morning everybody's exhausted, and Mama and Papa fall asleep on the couch.
The best part: "The movie made the cubs feel very magical." Also, "You can look fabulous tomorrow."