As the first day of school approached in July, Nikki Rajahn decided to give her two oldest kids a confidence booster — a personalized T-shirt.

She would make it with a Cricut crafting machine — but the design could be all theirs.

Brooklyn, 4, wanted glitters and bows. Six-year-old Blake, though, wanted to impart a message to encourage someone who might feel alone. After a year of teasing by his classmates and often feeling like the odd boy out, he hoped the misery would stop with him.

“I want a shirt that says, ‘I will be your friend,’ ” he told his mother. Anyone who doesn’t have a friend, he explained, will know that they have one already.

The sentiment didn’t surprise Rajahn, but it just about made her cry.

“I was so proud of him,” she said.

Much of Blake’s first year in elementary school had been tough. Being a little guy, he was an easy target for school bus bullies. He didn’t complain a lot about being picked on but every day he arrived home, Rajahn could see the defeat in his face.

To suddenly realize his experience hadn’t hardened him was like heaven opening up, a special moment to be shared.

Rajahn logged onto her Facebook page that evening to brag on her son.

After briefly recounting the conversation she had with Blake and his response, she ended the missive with this: “Never underestimate your kid’s heart for others! I love my sweet Blake! #stopbullying.”

Although most bullying happens in middle school, between 1 in 4 and 1 in 3 U.S. students say they have been bullied at school.

The most common types are social and verbal bullying like what Blake experienced.

According to the National Center for Education Statistics, of those students who reported being bullied, 13% were made fun of, called names or insulted; 12% were the subject of rumors; 5% were pushed, shoved, tripped or spit on; and 5% were excluded from activities on purpose. The vast majority — 42% — reported that bullying occurred in the school hallway or stairwell, 34% in the classroom, 22% in the cafeteria, 19% on the school grounds and 10% on the bus.

Apparently, a lot of people can relate. More than 2 million people — some as far away as the Philippines, New Zealand and Africa — responded, spawning a full-fledged antibullying campaign.

“It was kind of crazy,” Rajahn said.

Media, too, got wind of the post. Rajahn’s story was featured on “Good Morning America” and parenting blogs. Producers at the “Today” show and Ellen DeGeneres’ show reached out.

Two weeks later, Rajahn launched I Will Be Your Friend, a nonprofit that raises money for random acts of kindness and supports other good causes.

To spread their message further, mother and son organized a schoolwide competition encouraging other students and kids in their community to submit antibullying designs and uplifting slogans.

The winning design, “Kindness Starts With a Smile” inside a multicolored heart, was cut and transferred onto T-shirts using Cricut cutting machines and materials.

They distributed the shirts in November to the school’s 600 students, faculty and staff — just in time for World Kindness Day.