The origin of the swine flu is the pandemic which killed a lot of people.
The swine flu insult is a codename for police. In police have a history of being identified as dirty pigs. The swine flu insult was invented so that cops would not know what people would be talking about. When calling the police officers pigs, the cops have the right to arrest you for hate crime, hence swine flu has replaced the pig terminology. The cops are unaware of the term.
Synonymns: rat, pig, snitch, police, cops, officers, rick Ross(rApper/correctional officer), jakes, snakes, etc
*police car passes by*
Guy-1: man it's the pi-
Guy 2: nah man, run it's the swine flu!