你想干嘛，英语怎么说啊！

what do you want ?
what's up ?
what are you thinking ?
都有这意思，看语境了

What do you want?
What's your intention?
这两句是意思是你想干嘛，有种警觉的意思
what do you want to do？
则表示问别人有没有什么计划打算之类的意思

what do you to do?

what do you want 或者so what 不同语境意思不同表达也不同

What do you want?

what do you want to do？