Party Washer
A person whom only washes their hands after using the restroom in the visible presence of others. If it "appears" that nobody is present (i.e. somebody is in the stall, or they didn't notice someone was in the room with them), or nobody is actually in the restroom with them, they will leave after using the restroom and not wash their hands.
Christa is a party washer. She only washes her hands in public bathrooms where other people may see her. But not if she thinks she's alone.