"a piece of cake"
something is very easy or simple
"let the cat out of the bag"
to tell a secret or spoil a surprise
"once in a blue moon"
very rarely
"under the weather"
means not feeling well or feeling ill/sick
"slipped my mind"
means someone forgot something
"cost an arm and a leg"
something is very expensive or cost a lot of money
"sleep on it"
to think about it more or take more time to figure things out
"see eye to eye"
to agree on something or see things the same way
"when pigs fly"
means it's never going to happen or something that seems impossible
"hold your horses"
means to wait a minute or to be patient
"in hot water"
to be in trouble
"couch potato"
means lazy or laying around all the time
"call it a day"
means it's time to stop, quit or leave
"all ears"
means that someone is really listening or paying attention
"on the fence"
means not to be able to decide something
"get cold feet"
to be nervous or afraid to do something
"could eat a horse"
means that you are extremely hungry and could eat a lot
"break a leg"
means you wish someone good luck before a performance
"night owl"
someone that stays up late
"pig out"
means to eat a lot
"in the same boat"
to be in the same situation
"pulling my leg"
means playing a trick on me or fooling me
"a rip off"
means something is way too expensive
"to get up on the wrong side of the bed"
to feel irritable; to be in a bad mood
"raining cats and dogs"
means that it's raining really hard