The Unicorn poops Skittles, not M&Ms. Although I don't possess the documentation, photos or video to back this up, it's a known fact and a 2008 campaign promise made to those who have a strong desire for Skittles. Case in point - What was Travon Martin carrying the night he was casing the wrong neighborhood?
Yes, the Mk I Mod 0 Unicorn-S poops Skittles. The Mk I Mod 1 Unicorn-M poops M&Ms.