The “Lemons for Leukemia” campaign has become a social media hit. It’s the latest viral video effort to raise money for disease research.

When life hands you lemons… you take a bite and film it for YouTube. That’s how the adage goes, right?

It is if you’re 21-year-old Chris Betancourt and 19-year-old Dillon Hill, best friends and founders of Lemons for Leukemia, a social media campaign aimed at raising awareness for the bone marrow registry.

In late 2017, Betancourt was diagnosed with chronic myeloid leukemia. Without a bone marrow transplant, doctors told Betancourt he had just one year to live.

When he heard his friend’s news, Hill decided to take time off from college and help his buddy live every one of those days to its fullest. The two wrote Betancourt’s bucket list, everything he’d like to accomplish as long as he’s able, as a roadmap for their adventures and goals.

“When we first had that phone call recently and he was re-diagnosed, he said he was afraid of not being able to experience some things in life that we all plan on doing, so we kind of just decided to make a bucket list and document every single moment of it,” Hill told “Good Morning America.” “I couldn’t sit in a lecture hall while he was potentially dying.”

The friends are finding many wonderful events and firsts to do together — flying a plane, smashing guitars, being on TV — and documenting each of their adventures on their site One List, One Life and their YouTube channel.

In addition to checking boxes on the list, however, the duo hopes to possibly save a few lives in the process — and make other cancer patients’ dreams come true, too.

The Lemons for Leukemia social media campaign calls on participants to take a bite (or a squeeze) out of a lemon, film their puckered face reactions, share it on social media platforms, and challenge others to do the same.

“I originally came up with the idea because of the sour taste chemo leaves in your mouth,” Betancourt told Healthline. “It’s not a pleasant experience, but you’ve just got to bite in.”

The goal for the campaign is to raise awareness for the bone marrow donor registry and encourage individuals to sign up to be a donor. It’s a simple act, but it’s one that could save someone’s life, possibly Betancourt’s.

To become a donor, you can register online with the National Bone Marrow Donor Program.

A free cheek-swab kit will be sent to you. You’ll collect a sample and return the kit to the registry. If you’re matched with someone on the registry, you’ll undergo an out-patient procedure to extract bone marrow for the donation.

On March 1, Hill and Betancourt set out to complete a bucket list item (“Set a world record”) and add as many names to the registry as they could. Their challenge was heeded by more than 3700 people, which was indeed a world record for the most number of donor list sign-ups in one day.

As word of the challenge continues to spread, and more pucker-inducing videos of people eating lemons are shared, the list is gaining even more names and attention. Actor and comedian Danny DeVito even recently joined Betancourt for a few bites of a lemon.

“We started off begging and almost paying our friends to film themselves with a lemon,” Hill told Healthline. “We didn’t expect it to explode so quickly. It’s incredible.”

If the script for Lemons for Leukemia feels familiar, that’s because it is.

Building on the success of several other charity video campaigns like the ALS Association’s Ice Bucket Challenge, which raised more than $100 million for the organization, stunt campaigns proliferate in the social media world.

In fact, they’re quite common, which means they’re not always very successful.

“A huge number of viral videos are cooked up in company marketing departments and released into the wild on a daily basis. Others are dreamed up by individuals in hopes of going viral,” Daniel Levine, a trends expert and keynote speaker, told Healthline. “Every few weeks, one seems to succeed. While many companies and basement YouTubers try to nail down the formula for viral success, at the end of the day, it’s like putting any product out there: you do your best and hope for market-pull.”

Authenticity is one element of success, said Michelle Kubot, marketing director at Ambrosia Treatment Center, and not everyone has it.

Campaigns such as Lemons for Leukemia, however, reach an emotional peak with people based on the campaign’s authentic call and response.

“Lemons for Leukemia defied the odds because it wasn’t just a copy-cat campaign. It was 100 percent authentic,” Kubot told Healthline. “Most of our social media feeds are covered with smiling photos that have been staged and filtered until they hardly represent reality. Authenticity, therefore, stands out, and it’s not authentic to copy someone else’s successful campaign. Having a challenge just to have a challenge is not going to get results.”

Perhaps that’s what makes Lemons for Leukemia stand out in a world of no-shave months, no-makeup selfies, and hot sauce eating challenges.

It’s a campaign born from an immediate need — a bone marrow match could save Betancourt’s life — but it’s a bigger initiative, too.

The more people who know about the registry, the more who will sign up. Every potential donor is a potential life saved and another day someone gets to mark things off their bucket lists.

Currently, Betancourt and Hill are trying to recruit Dwayne “The Rock” Johnson to lift weights — No. 13 on the list — and they’re making good on their promise to give back.

“We want to help other cancer patients experience things from their bucket lists,” Hill said. “We’ve got some exciting things in the works.”