dumb-ass       
 adjective uk/ˈdʌmˌæs/ us/ˈdʌmˌæs/
 US informal愚蠢的,笨头笨脑的 
stupid
  My dumb-ass brother lost my phone. 我那蠢货弟弟把我的手机弄丢了。 
 It was a dumb-ass mistake to make. 这是一个愚蠢的错误。 
 dumb-ass       
noun [ C ] uk/ˈdʌmˌæs/ us/ˈdʌmˌæs/
 US informal傻蛋,蠢人,傻瓜 
someone who is stupid
  Some dumb-ass left his keys in the front door.
 Don't be a dumb-ass.