The action of lying on the ground, on your belly or your side with your hands either together above your head or on your sides, then flailing as to simulate the pokemon "magikarp" using splash attack. or any fish in general.
The start of this seems to be from anime conventions and a spin-off and response to planking, as the action is usually recorded not photographed.
Is he suppose to be a fish out of water? No he is just magikarping around.
When you flop around on your partner like a Magikarp, thus entering the sex position Magikarping (WARNING: May cause you to evolve into a Gyarados and use Hydro Pump)
I was having sex with my girlfriend and started flopping around on her like a Magikarp to preform the Magikarping sex position.
Magikarping is a technique in Grand Theft Auto V, it means to jump and then flopping mid-flight to achieve laughs or in some cases injure people who you go into.