Another name for H1N1 flu, or swine flu. So called because of its alleged origins in Mexico.
Bill: Hey, aren't you going to the concert tonight?
Wayne: Na, man... I caught that damn Fajita Flu and I'm sick as hell.
Bill: Go get some Tamiflu. You'll feel better soon
Wayne: Na, man... they're only giving that to illegals on medicaid and their 9 anchor babies.