silly             
adjective uk/ˈsɪl.i/ us/ˈsɪl.i/
B1 愚蠢的,傻的
showing little thought or judgment
  Don't do that, you silly boy! 不要那么干,你这个傻小子! 
 a silly mistake 愚蠢的错误 
 It was silly of you to go out in the sun without a hat. 你不戴帽子顶着太阳出门真是太傻了。 
  尴尬的;担心被他人嘲笑的
embarrassed; afraid that people will laugh at you
  I feel silly in this dress. 穿这条裙子让我感觉很傻。 
 Synonym: foolish
 B1 不重要的;不严肃的;不实际的
not important, serious, or practical
  She gets upset over such silly things. 她会因为这样的小事而难过。 
 We were served our drinks in these silly little glasses. 我们的饮料是盛在这些不实用的小杯子里端上来的。 
 - More examples
- What's the name of that guy on TV - you know, the American one with the silly voice?
- They can't expect me to accommodate all their silly little likes and dislikes.
- Why are you putting on that silly voice?
- I screamed myself silly on the roller coaster.
- Seriously now, did he really say that or are you just being silly?
Idioms      
drink, laugh, etc. yourself sillyidiom  喝得烂醉/笑糊涂了
to drink, laugh, etc. so much that you are unable to think clearly or behave with good judgment
  I laughed myself silly at his jokes. 他的笑话让我笑糊涂了。 
 silly billyidiom  informal 傻瓜(尤指孩子)
a silly person, especially a child
  You're being a silly billy, now stop it. 你在犯傻,快停下来。