One who can have sex with a herpies infected person several times and still come out clean.
I'm a Ninja I'm a Herpes Ninja!
Man I got away with sleeping with that cuz I'm a Herpes Ninja.
I can sleep with her cuz I'm a Herpes Ninja.
A small, albeit herpes-infested ninja. He comes into your house while you are away and touches EVERYTHING.
Do you ever wonder why your room smells funny sometimes when you come home? That's a sure sign that the herpes ninja has paid you a visit.