y u no, cant+present perfect

I’ve seen this meme(kind of a comic) around that always says “Y U NO bla bla bla” but it doesnt seem correct to me, I think it should be “Why dont you…”

So I was doubting wether “why you no” it’s correct to say or is just slang like “aint no…”

Could someone tell me?

Also, I was wondering if this sentences is ok “She can’t have done this to me”. The thing is that the can + a present perfect statement looks awkward to me, maybe because I dont remember using it that way.

So, should it be like that or “She couldn’t have done this to me” or “She can’t do this to me” (I think this last one would change the meaning of it because they’re doubting something that the guy’s mom may have done already; no something she is about to do)

Well. That’s it I hope it’s clear. Thanks!

‘Why you no…’ is incorrect slang.
Why don’t you… is correct (Note the apostrophe)

She can’t have done… is fine.
She can’t do…
She couldn’t have done…
She couldn’t do…
are all okay with slight changes in meaning as standard with these tenses.

Oh so I guessed right! the second one was actually more worrying lol Thanks a lot!

To me, “Why you no … ?” sounds like a stereotypical imitation of English as spoken by a non-native speaker (e.g. by someone whose native language is Spanish or Chinese, perhaps).

Yes, it sounds like a spanish-speaker translating it. But this is what I was talking about: knowyourmeme.com/memes/y-u-no-guy
There are millions of that image on the internet lol

Right, but I still think it’s meant to be deliberately incorrect English in the style of a non-native speaker. Unless you know differently…