Disco pang pang; a circular ride with no seatbelts that moves up and down, left and right, and spins around just to make you fall.

Unfortunately for you the operator of the ride you were on purposefully tried to make you fall on the lap of the person next to you — and that happened to be Jouno.

you were holding onto the railing as tightly as possible, until you lost your grip and fell onto Jouno’s lap.