duffer
noun /ˈdʌfə(r)/
  /ˈdʌfər/
(British English, informal)- a person who is stupid or unable to do anything well笨蛋;傻瓜;不中用的人 - I was a bit of a duffer at school.我在学校有点笨。 
 词源mid 19th cent.: from Scots dowfart ‘stupid person’, from douf ‘spiritless’.
- I was a bit of a duffer at school.