Here is a nice big poster to decorate your wall!
It is likely this was a retail store display of some kind, commanding you to buy Sonic 3. Of course, the Sonic is styled in the same way as the famous "Uncle Sam" poster with pointing finger of long ago, and similar slogan. You can see a Robotnik-ified Eggman in the background, along with some Badniks, an explosion and Knuckles with Tails. The "Sonic" word is really quite flashy though, with shiny highlighted detail. This poster is BIG about the width of your door, and a bit under half as high.