He had VIP from who-knows-what-site.
Basically you get infected, die, auto respawn, and you're a glitched human who can be infected infinite times 'til time runs out.
But don't ever infect them on your main account, you'll most likely get banned.
After some research I found out that this was "Reverse Lifetaker" which lets you basically become super spy in a game, which cannot be infected because it never really came to nexons mind I guess. Easily patched of course, if nexon wasn't an idiot.
LOL. Being a Super Spy is not part of reverse lifetaking. That is called Character Hack. You can basically become any character ingame, including the blue zombie from fireteam