It’s the old nickname for an airplane that basically flies up high, then nosedives for a while. They originally set it up so astronauts could train in free-fall (since they’re, y’know, falling for a few minutes), though it seems like you can just hire them for whatever now. OK Go did a music video featuring a ride: https://www.youtube.com/watch?v=LWGJA9i18Co

I’m partial to Fall Out Boy, myself

I’m showing it as $18 right now.