Are those the beads around his neck from the promotional art from the first SNES game? A good friend of mine, SmithyGCN, is a fan of that game and mentioned that fact to me. He created his own redesign for Slippy, which included the beads. It's for a project of his that is his take on Captain N. He draws in an art style not unlike Don Bluth's, so you're probably in for a treat if you ever see his gallery!
Normally, I'm used to Slippy with a more chipper disposition, but he seems mellow here. It's either he worked all night or enjoyed something a little... Ummm... Let's just say green.