A dad asked for birthday wishes for his autistic son. Tens of thousands of people responded.

Daniel Harrison had two desires: to drive a car and to make friends.

While he’s still too young to get his driver’s license, his other wish just came true, after a tweet that his father shared on Daniel’s 15th birthday unexpectedly went viral.

“Daniel’s my son. Profoundly Autistic. Hasn’t one friend. It’s his birthday today. In his ECHP he wrote that his two wishes were to learn to drive and make friends,” Kev Harrison, who lives in Nottingham, England, wrote in a tweet on Sept. 28. “Please wish him a happy birthday. Please show him you care. Please share.”

What happened next left Harrison, 52, completely floored. Thousands of total strangers — including more than a few celebrities — sent birthday wishes for his son and offered their friendship. His tweet has been viewed more than 14 million times, and more than 122,000 people have liked the original post.

The overwhelming reaction, Harrison said, “blew my mind.”

He was compelled to post the tweet after he and his wife, Catherine, read Daniel’s education, health and care (EHC) plan, which is part of a government program that helps determine levels of support for young people with special needs.

In response to a portion of the document that read: “Things that are important to me or things I would like to do…,” Daniel wrote: “drive a car” and “make friends.”

“It broke our hearts,” Harrison said, adding that although his son attends a special-needs school, he hasn’t formed any friendships. “He walks around the playground on his own, in his own little world.”

Daniel is on the more severe end of the autism spectrum, his father explained, and for several years as a child, he refused to consume food. He is verbal but gives “standard responses only” and struggles to engage in conversation.

“He has been through a lot in his 15 years,” said Harrison, who also has a 20-year-old daughter. “He is a lovely, kind, sweet boy. He does not have a nasty bone in his body.”

In the hope of raising awareness about autism and making his son feel loved on his special day, Harrison decided to post on Twitter. He thought a handful of people, at most, would respond. Little did he know that his tweet would become the No. 1 most trending post in the United States.

“It was astonishing,” Harrison said. “I didn’t think for one minute that the response would be anything like it was.”

Within only a few hours of sharing the tweet, high-profile people with large followings began retweeting Harrison’s post, and thousands of birthday messages for Daniel quickly flooded the father’s Twitter feed.

Mark Hamill, who plays Luke Skywalker in the “Star Wars” films, was one of many celebrities who commented. He wrote: “For my friend Daniel,” along with a GIF that says: “The force is strong with this one.”

Journalist Jake Tapper, actors Russell Crowe and William Shatner, actresses Jane Lynch and Kristen Johnston, activist Erin Brockovich, plus several others, also wrote birthday wishes to Daniel.

His parents said he was overjoyed.

“He was jumping up and down,” Harrison said.

Along with the many celebrities who reached out to send Daniel birthday wishes, many parents with special-needs children commented on behalf of their kids, saying they would like to be friends with him.

An 11-year-old named Olly shared a poem for Daniel in a video message, and a 9-year-old named Lennie played happy birthday on the piano. A group of students in Indiana made a special birthday sign just for Daniel. Autistic adults also reached out, sharing messages of hope and offering reassurance that things will get better.

“Driving and making friends were my goals too; i got my license in august and this photo is of me at a friend’s wedding !!! you’ll get there, i promise you,” a Twitter user named Frankie, who identified as autistic, commented.

People from all over the world asked to send birthday gifts to Daniel, but Harrison said he asked them to instead “do something kind for somebody. I’m a strong believer that good deeds should be passed along.”

Again, people took his words to heart, and many Twitter users did good deeds in honor of Daniel’s birthday.

“I just paid for the order behind me at Starbucks,” one person commented.

“I donated to a local food bank,” another wrote.

While thousands of people called Daniel their new friend, one Twitter user pointed out something that Harrison found especially heartwarming: “You definitely have a great friend — your amazing dad!”

Harrison is still sifting through all the sweet messages and doing his best to read them to Daniel and respond to each of them.

He said he hopes the huge reaction to his tweet will encourage people to show kindness to those with special needs.

“If I have reached one person and made them look at another child differently, I’ve done my job,” Harrison said.