When I first started buying my own clothes in the 1980s, lots of things were offered in small. medium or large sizes, and some visionary labels were offering "extra large" sizes. The guidelines for the three basic sizes in shorts or underwear were based on waist sizes, with small being 30-32 inches, medium 32-34 and large 34-36. Because I was on the cusp of small and medium, and I just knew I was due for the huge growth spurt that would enable me to play above the rim, I bought medium stuff.
As I grew older and more sedentary, I, um, graduated to the large stuff, although I was still technically in the medium band. Things shrink, and looser is better than too snug in my view.
This weekend I went to Target to buy socks and underwear. Without looking closely at the package I threw a Hanes 4 pack of boxer briefs into my cart. When I got home I discovered that "large" is now for men with waistlines of 36-38 inches, rather than the 34-36 I was accustomed to. With the availability of double and even triple xl to complement the new paradigm, this is pretty telling evidence of what's going on in America.