Use the phrase "Don't you ___!" to mean "You really ___. Wow!" For example:

Don't you smell nice!

This only works with positive things; you can't say things like "Don't you stink!" This phrase is especially used to compliment how someone looks.

You stress the word "you" when you're using this phrase. Although the sentence is formed as a question, you should pronounce it as a statement, not a question.

You can also use "Aren't you (something)!" in the same way:

Aren't you smart!