Bath Tub Stickers. These are plastic re-stickable items that are not actually sticky. They'll adhere to any damp or very smooth surface, such as a tile or even a window. These are just stock-arts with an artificial water theme. Sonic is running from a sponge to a soap, and Knuckles is water skii'ing despite looking like he is standing around on the water's surface. And that random Jet Ski Princess Sally again.
