An absolute yes that implies far more than a simple yes. Alternately, an affirmative response with minimal energy.
"You mean they actually did XYZ? Yep.... long silence. Translation: "Yes, they did, can you believe they had the gall!"
"Are you going to sit there all day? Yep...." Translation: "Yes, I most certainly am, and there is nothing you or anyone else can do about it."