(I clarified this post after the original posting, which caused some confusion.)
Do athletic guys in middle school and high school still wear gym shorts between their boxers and their outer shorts or pants? What was the point of that, originally, before it just became cool? It seemed like everybody did that a decade ago. It doesn't make sense to me. I asked friends who did that why, and nobody had a reason; it was always something to the effect of "I don't know" or "I like it." But it isn't comfortable. Not at all.
Fashion, even middle-school fashion, is weird.