“I’m as fit as a fiddle.”

Used to express the idea that one’s vocal chords are so painfully taut that if you dragged a horsehair bow across them they would make an awful noise. Usually not spoken aloud.

“Raining cats and dogs.”

While this phrase is used to describe a heavy rainfall, the modern rendition of the saying has strayed quite far from the original, “Reigning cats and dogs,” which is a reference to the time period between 5000 and 4600 B.C.E., when cats and dogs ruled the planet and would often force humans to pour buckets of water on top of them so they could pretend to run through the rain romantically.

“It’s all Greek to me.”

Originally used by the Greeks to express the idea that a conversation topic really felt in their element, this saying is now mostly used to stereotype Mediterranean food.

“It’s not rocket science.”

A statement often used to clarify one of the things that a particular activity is not – usually rocket science. Frequently used to describe activities like riding a bike, learning the rules of a board game, being a good significant other, solving quadratic equations, running a washer/dryer, managing an email account, cooking hamburgers, installing Microsoft Word, writing grammatical sentences, tying a necktie, obeying traffic laws, and making paper snowflakes, among many others.

“Don’t count your chickens before they hatch.”

A reference to the famous lyric from the murder-mystery-musical Counting Chickens. The main character, Tabitha, is supposed to finish a song with the recurring line, “Don’t count your chickens before they hatch their evil plans!” but is cut short when she is chloroformed by a hen.

“What goes up, must come down.”

A euphemistic reminder that all erect penises will eventually become flaccid. It is meant to remind men that even if they think their erection will last forever, it won’t, so if they and another person want to use the man’s erection to have sex they shouldn’t wait a really long time to do so.