Cats are full of eccentric behaviors. They hate getting wet. Their tongues sometimes get stuck midway out of their mouths, known as a “blep.” And they’re really happy hanging out in bodegas.

Some of these traits can be explained while others are more mysterious. Case in point: when they stick their rear end in your face for no apparent reason.

Are cats doing this just to humiliate their hapless caregivers? What would possess a cat to greet a person with its butt? Why subject the person who gives you food and shelter to such degradation?

To find out, Inverse spoke with Mikel Delgado, a postdoctoral fellow at the School of Veterinary Medicine at UC Davis. According to Delgado, cats don’t necessarily perceive their rectal flaunting as anything aggressive or domineering. In fact, it might be a cat’s way of saying hello.

“For cats, it’s normal for them to sniff each other’s butts as a way to say hello or confirm another cat’s identity,” Delgado said. “It’s hard for us to relate to, but for them, smell is much more important to cats and how they recognize each other than vision is. So cats may be ‘inviting’ us to check them out, or just giving us a friendly hello.”

For a cat, presenting or inspecting a butt is a kind of fingerprint scan. It’s a biological measure of security.

Other experts agree with this assessment, explaining that cats use their rear end to express friendliness or affection. Raising their tail so you can take a whiff is a sign of trust. If they keep their tail down, it’s possible they might be feeling a little shy.

If you think this situation is eased by the fact you rarely hear cats fart, we have bad news. They do. Because they don’t often gulp air while eating, they just don’t have enough air in their digestive tract to make an audible noise. Rest assured that, statistically speaking, there will be times a cat giving you a friendly greeting is also stealthily farting in your face.

[h/t Inverse]