[Grammar] Why did you do that!!

[sky3120]

Why did you do that!! VS. Why would you do that!!
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How do the expressions sound to native English speakers and what is the meaning or nuance difference between them?
Thank you as usual and I am happy to have you here!!

Ah...One more thing. If I say "tell me about your name, please" to get someone's name. Does it sound awkward?

 

[Rover_KE]

I'd say 'Why did you do that?' (with a question mark and not two exclamation marks if I had to write it down) if I wanted an explanation of something you'd already done.

But I'd say 'Why would you do that?' if you proposed a course of action which puzzled me.

Please ask unrelated questions in separate threads.

Rover

 

[sky3120]

Thank you and sorry. From now on, I will do that.

 

[emsr2d2]

In BrE you will hear an exclamation of "Why would you do that?!" after someone has done something inexplicable.

- I went out and got very drunk the night before an important job interview.
- Oh my God! Why would you do that?

The difference, for me, is that when you ask "Why did you do that?" you are actually expecting an explanation. However, "Why would you do that?" (after the event) is simply an exclamation of amazement that the person has done something so stupid. Asking "Why would you do that?" before an event (as in Rover's post) would require an explanation in response.