This phrase means "to await an event causally linked to one that one has already observed". In the form "drop the other shoe", meaning "say the next obvious thing" or "end the suspense", it dates from the early 20th century. It derives from the following joke:
A guest who checked into an inn one night was warned to be quiet because the guest in the room next to his was a light sleeper. As he undressed for bed, he dropped one shoe, which, sure enough, awakened the other guest. He managed to get the other shoe off in silence, and got into bed. An hour later, he heard a pounding on the wall and a shout: "When are you going to drop the other shoe?"
Markus Laker reports that The Goon Show (a 1950s BBC radio comedy) made reference to this. The character Eccles was an idiot and a bit of a freak.
"What's that noise?"
"Oh, that's just Eccles taking his boots off."
这个短语意思是“期待一件注定与已观察到的事相关联的事情”。用"drop the other shoe"这个形式表示“说下一显而易见的事”或者“结束悬念”，可追溯到二十世纪早期，它起源于一下笑话：
马库斯·雷克报道说《The Goon Show》（二十世纪五十年代BBC电台的广播喜剧）涉及到了这个。角色艾克勒兹是个白痴而且有点怪异。