冷不丁的做某事意思是毫无准备的做某事。

To do something "cold" means to do it without any preparation.

他在吊床上摇晃着，冷不丁剧烈一颤，以减轻他感受到的炎热。

There he was, swaying in the hammock with violent lurches to ease the heat he felt.

然后，冷不丁的这些视觉上的德性，你看它们好像它们是艺术。

And then all these sudden visual virtues, you look at them as if they were art, as if they were art.

一个地方如果女士过多，那么这个地方阴谋也更多，到处是陷阱，冷不丁的就有人在你后面捅一刀。

If a place have too much women, then this place has more plot, full of traps, rather abruptly in the back stab someone in your knife.

与其面对面谈话时，冷不丁突然跳到“当初我为啥疏远你”之类的不愉快话题，还不如跟大伙一起出去玩，这能让你们跟别人自由互动，从而减轻尴尬的情绪。

Rather than jumping into a serious discussion of why you drifted apart, you'll be socializing with other people or enjoying some entertainment, which can make your reunion less awkward.