Someone who is lazy, frumpy, unmotivated, and apathetic. A Buttertub never questions logic or consequence, and simply indulges on every gluttonous activity that gets in his/her way. Any activity or desire is usually resolved with the quickest, laziest and most unhealthy solution.
The origin of "buttertub" comes from the road "Buttertubs Drive" in Nanaimo, BC, Canada.
John: "Bitch, that's the 4th Big Mac/Slurpee combo you've had today, and why didn't you go to work?"
Jill "I dunno, shut up, I'm watching my show... Can you carry me to the toilet, I'm too lazy and i gotta take a dump."
John: "God damn, how did I get married to such a buttertub."