The Man in a Cow Costume is a character in Pooch Cafe. He works at fast food restaurants, promoting their food.
He first appeared in the "Pooch cafe, Poncho year one" flashback. A young Poncho and Boomer, thinking he'ed give them a hamburger, chased him. He then took off the cow head, causing the two dogs to think him a zombie cow.
Several years later, an adult Boomer and Poncho, along with Hudson, pursued him. He thought they were going to eat him, but they just wanted coupons.