What is a better way to say the phrase 腳都軟掉? Popular in Japanese anime and cartoons, after someone says something "cringy", you often see people falling down and having their feet in the air. What would be a good way to describe this phenomenon, both in Chinese and English.
I suggest 「翻倒」and  that is "flipped" in English

Example:

「他此言一出，眾人翻倒」; "Once  he said that, everyone flipped"

Also, in this kind of scene, the audience was figuratively "being knocked out" or "floored". I found the idiom "blow someone away" be a good match, and from the example sentence, I found "knock someone off their feet" suit even better.


  http://idioms.thefreedictionary.com/blow+away
  
  Blow somebody away also blow away somebody:
  
  
  To cause someone great pleasure or surprise knock somebody off their feet 
  
  
  "Everyone I tell that story to, I mean everyone, is just blown away." 
  
  Related vocabulary: blow your mind


Example:

"Once he said that. Everyone was blown away!"

"His stupid words knock everybody off their feet!"

"His stupid words floored everyone!"

As for Chinese slang, 「雷倒」http://baike.baidu.com/view/1816380.htm describe the reaction scene  very well.

Example:
「他的蠢話，雷倒眾人」