老外说“smokinggun”是指什么意思？冒烟的枪可还行？(2)

例句：
[Nixon] had also been listening to some of the disputed tapes, and he had found one—the"smoking gun"—that threatened to destroy his whole case ……This tape recorded Nixon …… ordering a cover-up, planning to use the FBI and CIA to protect himself.(出自：TIME, May 2，1994，p. 42 )
〔尼克松〕也在听一些引起争议的录音带，而且找到了一卷——也就是后来媒体称之为「冒烟的枪」那卷录音带——可能会将他整个的抗辩推翻……带子上录有尼克松……命令手下掩饰，并计划利用联邦调査局与中央情报局来保护自己。
not jump the gun
英文释义：
To do something too soon, especially without thinking carefully about it.
中文尤指不经仔细考虑，过早的行动。

例句
They"ve only just met - isn"t itjumping the gun to be talking about marriage already?
他们刚认识，现在就谈婚论嫁是不是为时尚早？
gun-shy
表达“迟疑、顾及”，
英文释义：Afraid of the consequences of an error while attempting to re-do something.