you're a star
Originally from Ireland, this all round compliment means you're a great person, you've risen to the occasion and been generally wonderful. It existed before the whole 'movie star' thing so it must relate more to a star in the sky.
Ah, thanks for bringing milk round for our cup of tea, sure you're a star!
you're a star
go fuck yourself.
I really appreciate your help Janel, you're a star....