Sitting on the Bouncy Seat

The bouncy seat presents a unique set of challenges for me. I'm kind of a slouchy sitter and when I get tired, I get really slouchy. Well, the bouncy seat is pretty good for my slouchy sitting style, but it seems like I slowly drift to one side of the chair until I'm in nearly a horizontal position and am half dangling off the side. Yesterday was an extreme example of this. I drifted off until my head literally was hanging out past the side of the chair suspended over the floor. I looked sort of like this
...cccc
o--|--c
...../\

where the "o" is my head, the "c"s are the chair and the other items are my arms and legs.
Even more amazing is that despite how uncomfortable this looks, I was able to rest comfortably this way for awhile. My Daddy would prop me up to a more normal sitting position and I would slowly drift down again. We played this game for several times until he came up with the idea of erecting a wall to keep my head vertical. Ah.