kick back


explanation : 
To "kick back" is to relax and enjoy your free time. It may come from the idea of putting your feet up and taking off your shoes. You can also use the idiom in the form "kicking back". 

e.g. I'm just kicking back with some friends watching the ball game.

Warming: Don't confuse this idiom with 'kickback' which is spelled the same way but has no space between the words. 'Kickback' refers to a bribe or payoff.