I know it's extremely early but..

So my sister and I always start to plan our halloween costumes at this time of the year because (usually) they're extremely elaborate and she agreed to do a duo costume with me which will be an insane asylum escapee and we need to pick one main thing our character is completely obsessed with. Mine is rats, mainly because I have two pet rats and will be incorporating them into my costume. We can't figure our her obsessive trait. We need something really unsettling. All we have is
1. Teeth.
2. Cannibalism
Any ideas?

Edit:
I'm talking about things that her teachers in her school will think:
"Why didn't we make a rule about this?"
And make people's stomach turn upside down c:<

 

Gore?

 

Cannibalism?