"Why are you so stupid?" in Japanese
I want to know how to say this to a certain someone who annoys me as a joke :3Also "Please give me your life"Arigato :3

Question

"Why are you so stupid?" in Japanese
I want to know how to say this to a certain someone who annoys me as a joke :3Also "Please give me your life"Arigato :3

Answer

Why you want to ask/say/tell such things....
Simplest for - like - 'You are idiot' - 'omae wa baka desu'
If you really want to use "Why are you so stupid?" can say - 
[naze omae wa sonna baka desu ka]

Answer

あんた、なんでそんなに頭悪いの？

Answer

just say "baka"