Sonic Crackers was an old prototype game shown for the Sega Genesis back in the early 90's. While many thought it would become Sonic the Hedgehog 4, it was scrapped and never released as a proper game. The main gimmick that people could see was the two rings connection between Sonic and Tails.
An idea later transplanted into Knuckles' Chaotix on Sega 32X. Which was a huge mistake.
So I guess Sonic was glad he gave his buddy Knuckles the bad game-play idea?