Sweet-potato-sauce is an exclamation similar to 'cool', 'awesome' and 'sweet'. It is used mainly because of its superior syllable construction. It often seems insufficient to simply say 'sweet!' when you find something pleasing. However, 'Sweet-potato-sauce' has, at 5, the perfect number of syllables. You might laugh, but it is the best way of expressing you contentment.
Person1: Hey, were you able to finish the summer reading?
Person2: Yeah, I finished the whole thing!
Person1: Sweet-potato-sauce!
Phil: What do I know about Clayton homes? I know they are built right here in America
Ms. Kay: And they know the difference between a house and a home.
Phil: Hey Ms. Kay, a home is where you get your famous sweet potato pie, honey.
And y'all know how we try to make Ms. Kay happy, happy, happy.
Clayton homes! Good call. *Duck noise*