Why are photos and videos of cats high-fiving suddenly popping up on Facebook and Instagram?

Ask Jackson Galaxy, host of Animal Planet’s "My Cat From Hell."

Last year, Galaxy launched Cat Pawsitive, a program that encourages animal shelters to teach cats how to do tricks, like giving high-fives, to make them more attractive for adoption. Shelters across the country, including KC Pet Project, have been participating.

The premise is simple. A kitty who can sit on command, jump through a hoop, give a paw bump or a high five demonstrates to a prospective owner that it can listen to instructions and connect with others.

A high five can make a shy cat open up and more aggressive cats play nice, Galaxy preaches.

Another benefit: Shelters can be a scary place for animals, and activities like learning tricks are a good stress relief.

Big life changes can lead to cats losing their mojo, their confidence, their "raw cat essence," Christie Rogero, program manager for Cat Pawsitive, tells Mother Nature Network.

Cats can withdraw and shut down in a shelter setting.

"When they arrive in a shelter, they may have lost the only family they’ve ever known, or they may have come from a difficult life as a stray on the street," Rogero said.

"We help those cats to feel more confident, to feel safe interacting with new people, to even spend more time at the front of their cages actively soliciting attention than hiding in the corner with their face to the wall.

"They get the kind of enrichment that cats need to be themselves and show their true personalities to potential adopters. This helps them to make connections and to get adopted more quickly."

Ahead of National High Five Day on Thursday — who knew that existed? — Galaxy is having a contest, inviting animal shelters and pet owners to post online photos and videos of cats giving high fives, using the hashtag #CatPawsitive and the tags @TheJacksonGalaxyProject and @HaloPets.

Entries are rolling in.

HAVE. YOU. EVER?

"Training a cat to do tricks is not as hard as we would think," said Stephen Holdeman, manager of feline behavior and training at KC Pet Project. "All we need is the right amount of patience, timing and motivation."

He explained how he does it.

After he finds out what kind of food the cat likes, Holdeman uses a technique called "operant conditioning," which associates a cat’s action with the prediction of getting a reward such as a favorite food or treat.

He also uses a clicker, a popular training device that makes a clicking noise.

"In the initial stages, we get the cat used to the idea that when it hears the sound of the clicker, one of its favorite treats appears," Holdeman said.

"After we have bridged these two ideas together, we can use the clicker to reinforce different actions the cat does to let them know that if they repeat it, they will get a treat."

Then he tries to get the cat to "target" something with its paws, usually getting them to play with a wand or toy. He "clicks" the clicker when the cat touches the object with its paw.

TIMING IS IMPERATIVE

"Making sure the timing of the click is lined up with the action we want is important, so the cat doesn’t start to ignore its relevancy," he said.

"After several repetitions, the cat starts to link everything together, and learn that when they touch the specific object, they get a treat, and they’re happy to repeat it. Now all you need to do is let your extended hand be the target, and we’ve got a high five."

So far, about 30 shelters across the country have worked with the Cat Pawsitive program, with another 50 expected to participate this year, according to Mother Nature Network.

More than 400 cats who participated were adopted during the first two semesters of the program, created by The Jackson Galaxy Project, a charitable program of GreaterGood.org.

It’s a free program for shelters and rescues, with sponsors including the Petco Foundation and Halo Pets picking up the tab for training materials, online classes and other things such as training treats.

And what about all those high five photos and videos?

After Thursday, Galaxy will judge them, and five finalists will receive cash and prizes for the animal shelter or rescue of their choice. Grand prize is a $5,000 cash grant and 10,000 bowls of Halo pet food. More info is at felinehighfive.com.