I'm not talking about the meat itself. Could be a corpse or something lifeless.
I think I've heard of the term "lamb" (British English). Is that the case though? (as lamb is sheep's meat).
EDIT: Eventually the context I heard the word was not meat specific. Also the word is "lump" as an answer in the comments.
Usage: - I won't stand a chance against a big lump like you (ref)