chill out  


explanation :
This is another piece of advice you can give to someone who's agitated or angry.  There are a lot of variations on this popular idiom.  You can say that you're just chill in or that it's time to chill. An older idiom that is no longer used much is to tell someone to 'take a chill pill'.  

e.g. I'm tired of hearing you yell about my nose rings! Why don't you just chill out!