Sanitation

Me: [washing hands in bathroom] Ow!
Krista: What'd you do?
Me: The water got hot real fast.
Krista: Oh... That left handle is hot water?
Me: Yeah... wait... you didn't know that?
Should I be more concerned that it took her 12 years to figure out our bathroom sink or that she's probably not washed her hands at all these past 12 years?"