My grandfather often wore knickerbockers when playing golf in his youth.

knickerbockers 是名词复数形式，指"灯笼裤"，特指膝盖以下收紧的宽松短裤。这个词源自19世纪纽约早期荷兰移民后裔的典型裤装款式，后来成为高尔夫等运动服饰的专称。