Snake: Colonel, who's this guy? He looks like a mutt.
Knuckles: I AM NO MUTT!
Snake: And he's got good hearing, too.
Colonel: That's Knuckles the Echidna, Snake. He appeared in Sonic 3 as a villain at first when he was tricked by Dr. Eggman into think Sonic and Tails had come to steal the Master Emerald.
Snake: Are you sure he's not a dog?
Colonel: He's not, Snake. He's strong, though. He once broke a mountain in half with a single one-two combination.
Snake: What? I'd better be careful of that mutt then.
Knuckles and Colonel: I'M/HE'S NOT A DOG!