TL;DR Don』t wear under-wear with liners. 以下來自 http://theclymb.com/stories/buying-guide-item/how-to-buy-running-shorts
UNDERWEAR/LINER: Run-ning shorts have a built-in liner and the rule of thumb is that you don』t wear under-wear with them because the extra layer of fab-ric can cause uncom-fort-able chaf-ing. Lin-ers pro-vide moisture-management to wick sweat away, which helps keeps things cool, com-fort-able and dry, and pre-vents infec-tion and chaf-ing. Addi-tion-ally, lin-ers are built to pro-vide enough sup-port and com-pres-sion for men so they don』t need a jock strap.