Sounds, physical sensations, scents, tastes, the way they're taking in the world. Fool the mind to fool the body, and the body will convince the mind what's going on. Usually took me a while to layer on the really elaborate ones so I'd ambush a sleeping cousin if they harassed me enough first. Favorite thing was to make them think they weren't awake. Sooo much scandalized everything if someone would say things they thought wouldn't be remembered.