This is a balloon.It's an object made by filling air into a sac made out of rubber or vinyl (or similar materials) until it expands.
POP!
If you tie two of them to your body, you can go to a stage where you fly through the skies while being chased by enemies that look like wild birds. There's also a sport where you score points by popping other people's balloons to knock them into the water below the stage.twitch