Ooh! I just had an idea that would seriously mess some players up, especially if you're the kind of DM who frequently uses "Creepy cute little girls that always turn out to be the villain or who turn on the party".

It only works, however, after they get so used to it that they automatically assume that ALL little girls are villains.

Once, then, they are sent on a creepy quest or are sent by a local leader down an evil cultist hideout, or something.

There, about halfway through, they meet an injured cute little girl, in the act of hiding (and she failed her hide check).

The players, obviously, will now assume that the cute little girl is the head villain.

After they complete the quest, and return to the village, a desperate woman runs up to them and asks, "Have you guys seen my little daughter? She was lost/captured/mysteriously disappeared a few days ago!"

Cue the adventurers having to return to the eerie crypt/cultist hideout just to find the little girl.

Then, after that, they'll always wonder if the cute little girls really are evil villains in disguise, or if they're actually cute little girls. Et...voila! You can use creepy little girl villains again.