Play Sonic the Hedgehog 2, and choose the 2-player mode. Now, complete a level that won't have a bonus after it. While transitioning from the score screen to the next level, a strange image sometimes flashes up. It seems to have Sonic and Tails sometimes, and a strange symbol (like a miniaturized version of the "ACT blah" thing) and some of the stats from the previous level.
Submitted by: kornyhatemachine