It's definitely a poke!
And it seems to have changed since I went in 2000. When I saw the show during my honeymoon, the stinger came out of the chair and jammed me in the spine. Not only did it hurt, it broke the skin. After the lights came up, I saw that the little poker thingie was stuck in its out position. So I walked away with a mildly bleeding back from that one.
During subsequent trips, I leaned forward, but noticed before-hand that the position of the poker was different. Sure enough, it's supposed to zing you in the butt now. However, sit the wrong way and you'll get jabbed like my poor female friend who shouted in the middle of the show "I've been violated!". Yeah, it sorta pokes in the center of your butt....
I have a customer who stops by who used to work on it for years. I'll hopefully be able to get a confirmation on the stinger location's change. Me? I'd just lean forward.