Whenever experts try to shed light on the baffling abyss that is cat behavior, they start by looking at how cats act around their own kind. To be friendly, cats often rub their heads, bodies, and tails alongside one another. It doesn't just feel good; that behavior also exchanges odors from the many scent glands located on the sides of a cat's head, the corners of its mouth, under its chin, on its ears, and — importantly — on its tail, including at the base and along the length.

Not only will cats rub their own scent on one another, but they'll also sniff their companions to confirm their identity, to see what they've been up to, and to generally just say "hello." That includes their butts, which also contain glands that are rich with scent information. Writing for PetPlace, Dr. Debra Primovic notes, "Some believe the 'sniff' can actually relieve tension and stress by helping an individual feel more comfortable about the other cat. Two cats living in the same house may smell each other when one comes in from the outside or comes back from the vet to confirm information about the cat's state including diet, stress, availability for mating, and mood."

Tail position is also really important when it comes to feline socializing. John Bradshaw, anthrozoologist and author of "Cat Sense: How the New Feline Science Can Make You a Better Friend to Your Pet," has researched how cats react to different tail positions and found that cats are more likely to approach and sniff a cardboard cutout of a cat with a tail pointing straight up in the air than one whose tail was horizontal, which led the cat to back away.

But that's with other cats. How does this apply to the weird way Snowball treats you? Well, when cats rub their bodies against one another, they generally move in opposite directions, starting head-to-head and ending with their butts facing one another. That's exactly what a cat is doing when it slides its body along your standing leg — its head starts the move, its butt finishes. But if you're lying down, that move isn't so straightforward and could end with your cat's butt in an unfortunate place.

Likewise, your cat may just shove its rear directly in your face because it wants to say "hello." Other cats sniff its butt in greeting, so why wouldn't you?

Finally, it's possible that it's just an accident. Since cats stick their tails straight up when they're feeling friendly, a happy cat exposes its stinkiest area to the world — whether or not there's an unlucky human face nearby.

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For more on why cats do weird things, check out John Bradshaw's book "Cat Sense: How the New Feline Science Can Make You a Better Friend to Your Pet." The audiobook is free with a trial of Audible! We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.