How do I say this in Korean?
"Why are you so cute" and stop being so cute" I want this to be in a complimentary why not negative way.

I also want to know how to say them in a formal and informal way.
Thanks.

Question

How do I say this in Korean?
"Why are you so cute" and stop being so cute" I want this to be in a complimentary why not negative way.

I also want to know how to say them in a formal and informal way. 
Thanks.

Answer

informal  : 왜 이렇게 귀엽니 그만 귀여워줘

Answer

Positive:
이렇게 예뻐도 되는거야? - Is it ok to be this cute?
이렇게 예쁜건 죄악이야. - It's a sin to be this pretty.

Context dependent, but overall positive:
예쁘면 다야? - Being pretty entitles you that much?
예뻐서 봐준다. - I'll overlook this time because you are pretty.