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