If you're used to doggy "kisses" and then experience a sweet kitty kiss, you're bound to be taken aback. Instead of being slick and slobbery, a cat's tongue feels dry and course like sandpaper. You'll probably think, "Hey, the rough tongue makes sense. Cats groom themselves and loosen dirt and debris from their fur with it," but this isn't the only reason a rough tongue comes in handy for cats.
Let's start with what makes a cat's tongue so rough. It's covered with tiny, backward-facing barbs called papillae that are coated with keratin, a fibrous protein that gives them strength. The papillae located in the center of the tongue are longer than those along the edges.
The barbs serve several functions, in addition to aiding with grooming. First, they optimize a cat's tongue for hunting because they help strip flesh from the bones of their prey. In addition, they help a mother cat stimulate her kittens to evacuate as she grooms them "down there," and cats also use their tongues for drinking. It might look like cats are lapping up water like a dog, but they rapidly dip their tongue into liquids instead. The papillae create a water column which your cat then closes his/her mouth around. This process is repeated a few times until there's enough water in the mouth to swallow. If you've noticed your cat doesn't swallow with every "sip," now you know why!
So, is their a downside to having a rough tongue like this? The answer is yes. The backward-facing papillae direct food and other things to the back of the mouth, making items such as string, tinsel, rubber bands, and hair bands difficult for your cat to spit out. And the barbs act similar to Velcro when they come in contact with yarn and other loosely woven or fuzzy things.
And of course, swallowing items such as these can be dangerous for your cat. It's best to put them away where kitty can't get to them. Honestly, hair bands are the most difficult for me. I have a tough time remembering to stash them in a drawer or container. And sure enough, if one happens to get away from me, my cat is all over it. She has developed hair band radar!