hot button

敏感问题, 一触即发的敏感事件 (来源：英语美食指南 http://food.englishcn.com)

a central issue, concern or characteristic, especially one that motivates people to make a choice (来源：英语麦当劳www.EnglishCN.com)

the principal desire that a salesman needs to "hit" in order to make a sale

(来源：EnglishCN英语博客基地)

n.Slang （名词）【俚语】
A psychological propensity for immediate or predictable response or reaction, as to a political issue or marketing tactic: (来源：英语麦当劳 http://www.EnglishCN.com)

即刻反应：作出立即的或必然的反应的心理倾向，如对政治事件或营销策略作出反应：
an issue that presses voters' hot buttons.
使选民作出立即反应的事件
Something that is of great interest or is known to elicit immediate or predictable response or reaction: (来源：EnglishCN英语问答中心[e问e答])

热门事物：令人极感兴趣的事物，或者能引起即刻或必然反应的事物：
a new product that is a hot button among young consumers.
在青年顾客中极走俏的产品 (来源：英语电影下载 http://bt.englishcn.com)