These are the best grabs I got of Eddie's Milbro slingshot and skull keychain. The skull definitely has red (rhinestone?) eyes but it's easier to see in motion as they sparkle red. I don't know the style of keychain, but the ring opens (to attach to the slingshot) and has a springy chain (about 2" long?).
I've found some excellent skull keychains on eBay for $3.00, but if you're really picky you may want to trade-out the ring style. You can also get Milbro slingshots for about $30.00 from Acorn Belts & Buckles.
ETA: Totally forgot, but you'd probably do better to get the whole skeleton keychain because you'll need the arm and leg bits to put on the back of the jacket! Thanks Scott! I found skeletons with red eyes for about $1 on eBay (still the wrong ring style).