Ever have a cold and tell someone you're "sicker than a dog?" Sick as a dog actually originates hundreds of years ago, if not longer. Some explanations say that in the 1700s, stray dogs were responsible for the spread of many diseases along with rats and other gutter critters.

What about working like a dog? Dogs are some of the laziest creatures around! For this one, you have to remember that dogs as "pets" are a relatively recent phenomenon; before that, they had to earn their keep by working tirelessly on the farm to herd and protect the animals.

This is a common idiom that we all use and accept. There's just one problem with it - pigs don't sweat!

So... what gives? You might be surprised to hear that 'sweating like a pig' actually has nothing to do with farm animals. According to McGill University: "The term is actually derived from the iron smelting process in which hot iron poured on sand cools and solidifies with the pieces resembling a sow and piglets. Hence, 'pig iron'. As the iron cools, the surrounding air reaches its dew point, and beads of moisture form on the surface of the 'pigs.' 'Sweating like a pig' indicates that the "pig" (i.e., iron) has cooled enough to be safely handled. And that's a "pig" you wouldn't want to eat."

Biting the bullet refers to sucking it up and doing something difficult, something you don't want to do but is necessary, and accepting the problematic consequences and/or pain that comes with it. But what does that have to do with biting a bullet?

There are different theories on this one. One common explanation is that in the olden days, it was typical for soldiers on the battlefield receiving surgery to bite down on a lead bullet. You've probably seen people in movies biting down on a piece of wood or leather strap. Since lead is a softer metal, it would give a little between their teeth and not damage them. So the idiom 'biting the bullet' means, okay, this is going to be awful, bite down and get through it.

To many parents, this common idiom can be rage-inducing. If babies sleep so well, why am I so exhausted all the time?!

Babies are notorious for waking up every few hours at the first sign of hunger or a dirty diaper. It puts their parents through the wringer (another strange idiom!). But to the outside observer, a sleeping baby is pure bliss. They are so innocent and blissfully unaware of anything going on around them. After all, if they're not sitting in a dirty diaper, they really don't have too many other things to worry about. Despite all their shenanigans, babies sleep a lot — around 17 hours a day. When you put it that way, the idiom starts to make a little more sense.

Why bother having a cake if you can't eat it? Am I right? That's the mystery of this common idiom (sometimes worded "you can't have your cake and eat it, too").

The explanation is actually straightforward. "Have," in this case, really means "keep" or "hold onto." So, in that case, it makes perfect sense that you can't eat your cake and also still have it. This means that "You can't have it both ways."

Well, I'm a big fan of having cake so that I can eat it! Naturally, I'd be washing it down with a fresh cup of coffee, too.