So a kid disappeared at a party???? (Monster involved?)

When my sim children check for monsters under the bed, the vast majority of times they don't find any so nothing happens except a look of relief on their faces and they then go to sleep. On rare occasions, they actually find one (in their imaginations of course, but we see the effects on screen) and then they are too scared to sleep in their own bed.

Or maybe the game knows I am too old to believe in under the bed monsters myself so the scenarios play out differently for me. ;)