A way to explain the unexplainable, especially unexplainable behavior, especially-especially taking matters into your own hands. It's name is derived form the actor who played Captain Kirk on Star Trek (William Shatner) who NEVER has to take matters into his own hands because he always has everyone else do everything for him, and every circumstance is neatly explained as being caused by the supporting characters. For example, Sulu will say to Kirk "the Romulans are attacking our ship" and Kirk will say to the Romulans "Why are you doing this to us? If you don't stop I'm going take this as your decclaring war on the Galactic Federation," then the ROmulans attack but all Kirk has to do is say "Fire phasers, Mr. Chekov" to resolve the situation. Kirk never lifts a finger, never takes any risk the others aren't also taking. An Anti-Kirk Moment is where you have no idea what's going on, no idea why things are happening, and it's up to you alone to take action.
Sulu says to Kirk "the Romulans are attacking our ship" and Kirk says to Mr. Chekov, "I'll take care of this situation myself, hold on for just a moment," then Kirk locks himself inside the Teleportation room, beams himself aboard the Romulan spaceship bare-chested and uses Ninja-like stealth to pacify and eliminate the Romulan crew. Then after dismantling the surveillance systems on the Romulan control deck, Caprtain Kirk quietly kills the Romulan captain and makes it look like a murder-suicide, and beams back aboard the S.S. Enterprise roughly under 5 minutes flat, makes a coughing sound while unlatching the door to the Teleportation room and force-puking on Dr. Bones shoes who screams "What were you doing in there?" to which Captain Kirk replies "I think I ate some bad dates" to which Dr. Bones replies "Captain, there's been a murder-suicide on the Romulan vessel and the Romulans are no longer attacking us", to which Captain Kirk smiles and says "Oh that's good news" and pukes more, to which I say out loud "that's an Anti-Shatner Moment" and also puke.