blunderer       
noun [ C ] uk/ˈblʌn.də.rər/ us/ˈblʌn.dɚ.ɚ/
 轻率行事闯祸的人
someone who makes a lot of serious mistakes, usually because of not taking care
  The chief constable is seen by some as a blunderer. 警察局长被一些人认为是一个轻率行事,易犯大错的祸头子。 
 We should be blaming the incompetent blunderers who got us into this mess in the first place. 我们应该归咎于那些能力差,轻率行事,一开始就把事情搞得一团糟的人。 
 See: blunder
 - More examples
 - Billy is a silly, insensitive old blunderer.
 - Who do this bunch of blunderers think they're kidding?
 - We had to helplessly watch as these blunderers threw the game away.