The nose’s first priority is to let you know when something stinks, literally. In fact, the smells entering your nasal passageways en route to the brain’s olfactory center can alert you to danger (as in the case of noxious fumes or smoke) or they can help you relax (aromatherapy is based on this principle). Pleasant smells are, of course, always welcome, but when an unpleasant stench comes on the scene, the nose often reacts by crinkling. This response is also suitable for expressing your displeasure with someone who may actually smell quite pleasant.

For example, you’ve just finished your workout at the gym. You’re supposed to pick up your friend for lunch, and since you’re running late, you don’t bother to hit the showers; you just grab your coat and run. When you pick up your friend minutes later, she climbs into the car and the two of you start chatting away. Soon, you notice that she’s looking around uncomfortably and pressing a tissue to her nose. You ask her if she’s sick; she says no, but still, that tissue remains blocking her nostrils. Without actually plugging her nostrils, she’s telling you that something stinks.

After lunch, you head to the office. You have a big report due tomorrow. You’re hard at work, when one of your colleagues pops into your office to discuss your thoughts. As you summarize what you’ve come up with so far, you notice that he’s crinkling his nose. Instantly, you start to panic. Do you smell?

It’s possible—the nose does initially crinkle when a hint of offensive waft hits it—but it’s more likely that this nose crinkle is an expression of the way your coworker feels about your report, and it isn’t good. The nose crinkle is used to convey displeasure or disagreement on some issue. You might see a woman crinkle her nose when an undesirable man asks her for a date, and you’ll also see nose crinkles when children argue with each other.

This isn’t a gesture that’s used to express a positive message, so when you see someone’s nose crinkle in response to something you’re saying, you might want to stop right there and get to the bottom of the issue.