Learn some common English idioms and the stories that lie behind them. We’ll show you what they mean and also how to use them in action. They include:
from the horse’s mouth
looking a gift horse in the mouth
bottoms up
rule of thumb
a red herring
best man
This is the third in a series of videos on the etymology of common English idioms – so their origins and history.
If you’ve ever wondered where an idiom came from, or how to use it in practice, you’re going to love this series.

What does it mean if you look a gift horse in the mouth?
Or you follow a rule of thumb.
And what happens if you follow a red herring?
We’ll show you what all these idioms mean and more.
And we’ll show you how to use them.
You’ll love it because they all have stories behind them.
Our first idiom is ‘from the horse’s mouth.’
If we get information straight from the horse’s mouth’ then we get it from someone who has direct knowledge.
I got a hot tip.
Oh yeah. What’s that?
Buy shares in ACME Corp.
Ooo, why?
Their shares are going up today. I got it from the horse’s mouth.
Ooo, who did you speak to?
I met a guy on the bus who met a guy in a bar who works in the mail room at ACME Corp.
That doesn’t sound like the horse’s mouth to me.
Hmm.
So when you can, you want to get information straight from the horse’s mouth.
The idea is if it comes from someone who’s directly involved, it’s more likely to be accurate.
The story of this idiom comes from horse trading. If you’re buying a horse, it can be hard to know how old it is, and how healthy it is.
You can’t trust the person selling you the horse, but if you look in the horse’s mouth, you can see by looking at its teeth.
You can get the truth from the horse’s mouth.
And next we have another idiom with the same origin. Don’t look a gift horse in the mouth.
This means that if someone gives you a present, you should be grateful for it and you shouldn’t look for things that are wrong with it.
Coffee?
Oh, thank you. Jay, this coffee mug’s got ‘engine oil’ written on it.
Oh yeah. It’s new. They gave it to me at the gas station.
So I’m drinking from a mug that says engine oil!
Stop complaining. It was free!
He’s never one to look a gift horse in the mouth.
The meaning here is it’s bad manners to criticize something you got for free.
If you say so. OK, next idiom. Bottoms up!
This means cheers. It’s something we can say to friends before we drink.
Cheers!
Bottoms up!
It’s an encouragement to drink, because if you put the bottom of the glass up, you have to finish it all.
You don’t really have to drink it all. It’s just something we say.
The idiom has an interesting history. Back in the 18th and 19th centuries, the English navy badly needed sailors and the king offered a shilling to men who would sign up.
But they still couldn’t get enough sailors so sometimes they employed press gangs to recruit people. These gangs actually kidnapped people and forced them onto ships. It was terrifying.
There were also recruiters who would go to pubs, buy men lots of drinks and trick them by putting a shilling in their tankard. The shilling was proof that they’d accepted the King’s offer and agreed to join the navy.
The story goes that pubs started using tankards with glass bottoms. They’d say ‘bottoms up’ to tell their customers to look for a shilling before they began drinking.
Is that story true?
Good question! It’s true that there were press gangs who forced men to join the navy, but I don’t know about hiding a shilling in your tankard.
It’s a good story anyway.
Yeah, next one!
Rule of thumb.
This is a way of measuring something. It’s not exact but it’s based on experience.
How long will it take you to edit the video?
Well, it’s hard to say because it varies.
Well. J ust give me a rough estimate.
As a rule of thumb, it takes about twenty minutes to edit one minute of video.
OK, I’ll work with that.
Or maybe thirty minutes.
So a rule of thumb isn’t an exact calculation.
But it’s a useful calculation because it’s based on practical experience.
So where does the idiom come from? One theory is it dates back to an English judge in the 17th century. He ruled that husbands can beat their wives with a stick if the stick is no wider than his thumb.
We’d glad to say that’s not true.
It’s an urban legend.
There’s no evidence for it.
The idiom probably comes from making flour with mill stones.
To turn grain into flour you set the two stones and run a little grain through. Then you test the flour by rubbing it between your thumb and forefinger and then you adjust the stones to make the flour as fine as you want.
I think that sounds much more plausible.
Yeah, me too. Plausible means reasonable and likely to be true.
OK next one. Red herring.
A herring is a kind of fish, a smelly fish. But a red herring has a different meaning.
It’s a fact that’s not important and that takes our attention away from the important facts.
Good detective stories have a lot of red herrings, clues that distract us and point us in the wrong direction.
Hmm. So how did he die Watson?
Well it’s obvious, Shelock. Somebody stabbed him.
I’m not so sure.
Really? But look. There’s a knife in his back.
That could be a red herring, designed to confuse us lead us down a wrong path.
Then how did he die?
It’s elementary my dear Watson. It was suicide.
Oh wow Sherlock! You’re brilliant!
So where does the idiom ‘red herring’ come from?
It comes from hunting. Hunters had to train their dogs to follow the scent, the smell of the animal that they wanted to catch.
In the past, they’d put smelly pieces of fish in trees to distract the dogs, and that way they could train them to ignore the scents that weren’t important.
OK, the last idiom. This is a quick one.
It’s one we think you’ll know: best man
When there’s a wedding there’s a bride, a groom, and a best man. He’s a close friend or relative of the groom.
So where does the term best man come from?
Well. one story is that many centuries ago sometimes there was a shortage of women. Rival families or tribes would try to steal the bride – to kidnap her and take her away.
The groom would ask ‘the best man’ in his village or town to help him. He might be the best swordsman and he’d have to be ready to fight to protect the bride.
These days the best man just has to hold the ring and make a speech.
Yes, it’s a much easier job now.
We hope you’ve enjoyed learning these idioms and the stories behind them.
Please give us a thumbs up if you liked them.
Now this is the third video we’ve made in this series, so if you liked it, you can see more.
And why not share this video with a friend. They might like it too.
Bye-bye everyone.
Bye now.