Lemons for Leukemia: Meet the best friends behind the viral challenge

They are hoping to set a world record and raise awareness for marrow donation.

— -- The two best friends behind the viral "Lemons for Leukemia Challenge" are attempting to set a world record today for the most donors added to the national bone marrow registry within a 24-hour period.

To learn more about how to join Be the Match's bone marrow registry, click here.

When Betancourt's best friend, Dillon Hill, 19, learned of the leukemia diagnosis, he took time off from college to help his dying friend fulfill his bucket list.

"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 said today on "Good Morning America." "I couldn’t sit in a lecture hall while he was potentially dying."

The pair created the challenge, a social media campaign that aims to raise awareness for bone marrow donations, and calls on partakers to record themselves taking a bit out of a raw lemon and then post it online and challenge someone else to take part.

Because a marrow transplant is the only treatment that could potentially save Betancourt's life, they are hoping to use the campaign to raise awareness for bone marrow donation.

"It’s been absolutely incredible, honestly," Betancourt said of the response. "I expected to maybe get 500 views on our YouTube video and within the first day we broke a quarter of a million so it’s absolutely astonishing to be here right now."

The pair are also encouraging people to sign up to Be the Match, the national bone marrow donation registry, and hoping to set a world record today by registering the most marrow donors within 24 hours.

Be The Match has facilitated over 85,000 transplants since 1987, and 6,100 just in 2017 alone.

Betancourt and Hill have completed 25 of the 128 items on Betancourt's bucket list, they said.

"Some of the things that we’re looking forward to right now are lifting weights with ‘The Rock,'" Betancourt said, referring to actor and former wrestler Dwayne Johnson. "The other thing that’s really far out there is go to space. You never know. I just have to put that on the list."

Roberts accepted the challenge, and took part in it today along with the other "GMA" anchors.

The "GMA" anchors were joined in taking the Lemons for Leukemia Challenge by "GMA" staff, audience and people across the country, from California to Minnesota and Times Square.

To learn more about how to join Be the Match's bone marrow registry, click here.