I was on a learning-Spanish forum earlier today and someone asked how do you say your breath stinks or you have bad breath in Spanish. And another person asked how do you say you have BO (body odor), your underarms stink or your armpits smell in Spanish.

No one had answered the questions but I thought that I would share the answers with my readers in case
you ever have the need to tell someone this:

Tienes mal aliento.
You have bad breath.
Your breath stinks.

And if you ever need to tell someone "tienes mal aliento" (you have bad breath) the following
phrase may also be helpful:

Necesitas enjuagarte la boca con bicarbonato y Listerine para desinfectarla.
You need to rinse your mouth out with baking soda and Listerine in order to disinfect it.

Yes, both Listerine and Colgate toothpaste are sold in Spanish speaking countries. But what I find so interesting is that in Spanish speaking countries they speak both Listerine and Colgate EXACTLY the
same way you would pronounce the words if they were from the Spanish language.

Here's another vocabulary word that may come in handy:

Enjuague bucal – mouth wash

And this is how to say have BO (body odor) or your underarms stink in Spanish:

Tienes mal sudor.
Your underarms / armpits stink.
(Literally, "you have bad sweat.")

"Tener mal sudor" is probably the most universal way to say in Spanish that someone has smelly underarms or BO (body odor). But in Colombia, the term that I have also heard used is "tener grajo" for "your underarms stink." For example …

Cuando yo era pequeño yo tenía un maestro que tenía grajo.
When I was little, I had a teacher who had smelly underarms, stinking armpits, BO, etc.

I was wondering if "tener grajo" might be a phrase that is only used in Colombia. So I looked the phrase up in one of my Spanish dictionaries and it says that the phrase is used in Colombia, Ecuador and Peru.

There is one more phrase that I have heard used in Colombia, to say that one has BO. And that's
is "tener chucha." "Chucha" literally means "opossum" as in the animal opossum.

Telling someone "Tienes chucha" (you have opossum) to say that one has BO makes perfect sense that opossums, like "zorrillos" (skunks) or "mofetas" (skunks), also have the ability to release a foul-smelling fluid when threatened.

By the way, here's how you say armpit or underarm in Spanish.

Axila (underarm, armpit)

Lávate bien la axila para que no huelas mal.
Wash you underarms good so that you do not stink.

Beside "axila" you may also hear Spanish speakers use the word "sobaco" for the English word underarm.

No te lavaste bien el sobaco. Por eso tienes mal sudor.
You did not wash your underarms well. That's why you have BO (body odor).

Before I go and while we are on the topic of "olfato" (the sense of smell), I have a mistake that I want to share with you that I heard an American friend make here in Medellín, Colombia earlier tonight
when speaking Spanish.

My friend, his "novia" (girlfriend) and I were at a bar having drinks. And then his "novia" went outside the bar to smoke a cigarette. When she returned, I heard my American friend say to her:

Tú hueles como cigarrillos.

That is NOT the correct way to say "you smell like cigarettes" in Spanish.

In Spanish you must use the "oler a" construction to say that something or someone smells like something. You do NOT use "oler como."

So he should have said to her:

Tú hueles a cigarrillo.
You smell like cigarettes.

The same rule applies when you want to say that something tastes like something. You must use the "saber a" construction. You do NOT use "saber como."

Esta torta sabe a chocolate.
This cakes tastes like chocolate.