"Flu Shot", by Randall Munroe, licensed under Creative Commons Attribution-NonCommercial 2.5 License
"Wait, how often are you getting bitten by snakes? And why are you boiling water?" "Dunno, the CDC people keep showing up with complicated questions about the 'history of the property' and 'possible curses' but I kinda tune them out. At least one of them offered me the flu shot."