That picture has been "making the rounds" for years. There's a copy of it at pretty much every marina on the planet. One of those boating classics.
I have seen a jetski launched "front first" by a H1 (real) hummer that drove in and did a U-turn on the ramp, then drove out again. It got deep enough for the jetski to float off the trailer.
I've seen that done with a pickup before, a couple times. It's actually not that rare, at least in the redneck areas of the Adirondacks. People are too cheap to buy a trailer so they just toss it in the back of the truck.