bomb a dropshell （消息）令人震惊，叫人吃惊

【例句】
Grandfather dropped a bombshell last night when he told the family he is marrying a woman 40 years younger than he.
祖父昨晚上对家里的人说，他要和一个比他年轻四十岁的女子结婚，这可真叫大家吃了一惊。

In March 1968 President Lyndon Johnson dropped a bombshell one of the biggest bombshells ever dropped in American politics when he announced that he would not run for re-election because of the Vietnam War.
1968年3月美国总统约翰逊宣布，因为越南战争，他决定不竞选连任。这可是美国政治历史上最令人震惊的消息之一了。