谢边边mm, 这个cold fish其实经常~~

指那些对人很冷淡，很不友好，根本没有意思和别人友好相处的人。这些人往往不受人欢迎。
Let's not invite Joe to the party: he's such a cold fish he'll spoil it for everybody else.

其实俗语中还有一个很常用的意思
A sex partner who is either not receptive, or not providing any emotional or physical feedback during ...

I am not trying to be "yellow" here, just explain a phrase...