infuquithable 

Someone who is in a state (physical, mental, social, etc) where they cannot be ridiculed, teased, taunted, joked about, or have shit talked to them. In short, they cannot be fucked with. Opposite of fuquithable (someone who practically invites negative attention onto themselves.)

Guy1: Man, I just tried to talk shit to Mark, and he just kept working; didn't phase him at all.
Guy2: Wow, completely infuquithable, huh?
Guy1: Completely.

Guy1: Hey, dude! Let's go kill THE MOB!
Guy2: Seriously?
Guy1: Yeah!
Guy2: Dude, they're, like, completely infuquithable, you know that?
Guy1: Damn!

infuquithable by Reiver102 January 28, 2011