A pronoun that can be used as a name for someone who is a couch potato. It is mostly used as a light-hearted insult. It is derived from the word spud, which is a word for a potato (or an idiot), and a wordplay on the name Spuds Mackenzie, the beer drinking adventure dog. Replacing "Mackenzie" with "McFuton" indicates the person in question is the opposite of adventurous, and is in fact a sofa dweller.
"We might have a clean kitchen one day if ol' Spuds Mcfuton over there would ever get off his rump and do some dishes."
Girl: "Does your roommate ever cook for himself?"
Guy: " Jeff doesn't cook. He's a real Spuds Mcfuton that guy. He'll just order order a pizza and 2-liter."