“你是谁？”口语

口语里，“Who are you？”已经是很随便了。

不过..
除了“Who are you？”
还可以说：
“You are..？”
“Who might you be？”

意思也是一样的～

这个就够随便了

Who the f*ck you are?
够随便了吧

你可以前边根据语境加点词，比如“but... who are you?”"uh... who are you"

who is it?有人敲门时