Big Chonker
A noun and term of endearment used to reference anyone or anything that is overweight, fat, chunky, portly, chubby, obese, flabby or rotund.
Person 1: Bro, look at how fat Olivia is! She's like a bucket of wrinkles!
Person 2: Oh she's a big chonker!
Person 2: Oh she's a big chonker!