chill out 
phrasal verb with chill verb [ I or T ] uk/tʃɪl/ us/tʃɪl/
 informal (also chill)      
B2 彻底放松;冷静;镇静
to relax completely, or not allow things to upset you
  I'm just chilling out in front of the TV. 我只是看电视放松一下。 
 Chill out, Dad. The train doesn't leave for another hour! 别紧张,爸爸,火车还有1小时才开呢!