Memory Game Idioms 2Online version Players will try to match the idiom with it's meaning. by Lunarn Smith Cost an arm and a leg Tell a secret Best thing since sliced bread Let sleeping dogs lie Burn the midnight oil Hold your horses Work until late at night Ants in one’s pants Very expensive Wait and be patient Good idea or invention Once in a blue moon Can’t stay calm (relax) because you’re nervous It’s not hard. Don’t start problems or cause trouble Let the cat out of the bag It’s not rocket science Happens very rarely; uncommon