Final answer:
The correct slang term for a clumsy or uncouth person is oaf.
Step-by-step explanation:
The correct slang term for a clumsy or uncouth person that is often preceded by "Ya big ____" is A) Oaf. An oaf is someone who is not very coordinated or graceful in their movements. "Lummox" is a term often used in a playful or teasing manner to describe a person who may be perceived as a bit clumsy or uncoordinated. It's a colloquial term that adds a touch of humor or affection to the description of someone's clumsiness.
The other options (A) Oaf, (B) Buffoon, and (D) Lout are also terms that can be used to describe a clumsy or uncouth person, but the specific phrase mentioned in the question is associated with "lummox."