Hesitance to engage in what is perceived as a possible bad trip. May also be used to refer to the onset of the bad trip.
I'm getting some serious tripidation about that 'shroom I just ate, guys.
Hallucinogen induced anxiety
Dude: "Shit man, I think that Peyote got me freakin out."
Other Dude: "What?"
Dude: "I keep seein weird shit man... I'm fuckin freakin!"
Other Dude: "Dude relax, just tripidation... Breath..."