|What a pantywaist!|
pantywaist. n. A child's undergarment consisting of a shirt and pants buttoned together at the waist.
That definition seems archaic, since I have never heard of a modern child being dressed in such a garment. But from this old ad I found, one can clearly infer that pantywaist in the modern sense must mean a content youthful person with well-managed hair who cares about his/her health, is comfortable in his/her own skin, and puts a premium on comfort and value. Plus: sexy knees.
Awww. He knows me so well.