Screw Flu
(n.) A synonym for a sexually transmitted disease. Applies to any ailment contracted during intercourse, e.g. herpes, chlamydia, influenza, etc.
After homecoming, Deb had to go to the clinic; she caught a touch of the screw flu.
Flu Screw
When you really want to have sex with someone, but it's evident they have the flu; fever, chills, stuffy nose. While it should be a deterrent and you're putting your own immune system at risk, you do it anyway.
Joe was only here for one night, sick as a dog, but I had to go for the flu screw because last time we saw each other he made me cum 9 times.