How does one procure Killing Floor guest passes?

try SteamTrades.com

Try asking google the right question :D

I remember vaguely that they were given out to folks who had killing floor during christmas or something like getting it when buying for a certain period of time.

Sacrifice your first born son to the mighty Cthulhu and when the sun rises two shall fall from the sky in a flash of light.

Well I got a couple from buying the game itself, and then a couple more for buying all the games DLC, but those are long gone :/

I got 2 from buying the game, however I've given one away and I'm waiting for this other dude to take his. If he dont get back to me soon, I'll hook you up breh

I got one for ya. Add me.

Add me in steam, got two passes!

EDIT: I gave the two, please don't add me!