yes. that's what I would mean if I say that, more than "why do you speak like that".
That sentence should be past tense and has nothing to do with the horribly offensive sentence provided. What DL is saying is that you have an odd lisp and sound retarded
- tại sao bạn nói như vậy? (why do you say such things?)
- tại sao bạn nói chuyện như vậy? (why do you talk/speak like this? [because you sound funny, weird, you used a dialect or an accent unusual to your natural speech, etc. so I'm wondering]
Is it 'nói' or 'nối'...?