when a man or lesbian is being driven crazy or sick by they're current or ex female partner (also known as a "bird" in the UK).
1st guy: Man did you hear about Andy's problems with his girl?
2nd guy: Yeah man, he's got bad bird flu.
1st guy: Dude, did you hear about how Martin's ex has been treating him?
2nd guy: Yeah, it's so bad, he don't deserve it at all. She's being so childish! Mart's got 1st degree bird flu!