Meaning: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'.

Example: 'I'm just kicking back with some friends watching the ball game.'

Warning: 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. 

Meaning:This is a very useful phrase to know! You can use this phrase when you want to warn someone. If there is immediate danger, yelling ‘Look out!’ will alert everyone to the danger. For example, if someone is crossing a street and a car is coming down the street at a high speed, you might yell, ‘Look out!’