Farra is wonderful, but....
...no one wants her to die. I know you don't mean literally, but still, extended underarms tickling like Farra endured on "Farra's Body" borders on cruel. I never bought the video, but I remember the clip and Farra's reaction. It was explosive. And yes, I enjoyed it, but anything longer than a few seconds of viscious tickling like Jeff was dishing out starts to seem...well, sadistic. Perhaps that's what some of us want--"Without Consent" and Gabrielle's similar video stand out as examples. Not this lad, though. Consensual with a touch of panic is good, but trust has to be there before any fun takes place.
But, more to the question: I imagine the mind would shut the body down before too long. That is, she'd pass out from lack of air. I honestly think death by tickling would be a long, horrible, drawn-out way to go. In NO WAY am I suggesting you or anyone else advocates this...just sharing my thoughts.