"I went to stretch it," the 28-year-old told The Washington Post, "and as I was using my hand to apply a little bit more pressure than I probably should have, I heard a pop."
Less than an hour later, Hader would be in a hospital emergency room unable to walk and suffering from what doctors told him was a "major stroke" caused by a tear in an artery in his neck that had formed a clot.
"He could have died," Vance McCollom, a doctor at Mercy Hospital in Oklahoma City who treated Hader, told KOCO this week.
McCollom said Hader had torn his vertebral artery, one of the major arteries in the neck that goes up into the brain.
A vertebral artery tear, or dissection, is known to cause strokes that can affect younger people in their 20s or 30s, and has nothing to do with a person's health, Kazuma Nakagawa, a stroke neurologist, told The Post.
While it's rare for neck popping to lead to a tear, it's not unheard of, said Nakagawa, the medical director of the Comprehensive Stroke Center at The Queen's Medical Center in Honolulu.
"People just need to know that sudden neck pain can potentially be the starting point of a stroke," Nakagawa said.
On March 14, Hader said he was working from his home in Guthrie, Oklahoma, when he felt the familiar soreness in his neck and tried to alleviate it.
"This wasn't me cranking on my neck trying to pop it as much as I could," he said. "It just ended up popping."
Almost immediately after hearing the pop, Hader's left side started to go numb.
Drawing from his experience as a former police officer, Hader said, he quickly checked to see if his face was drooping, one of the telltale signs of a stroke. The muscles in his face all appeared to be working fine, so he concluded that he must have just pinched a nerve and went to get some ice packs.
That's when Hader said he realized something was very wrong.
"As I'm walking to the kitchen, I quite literally could walk only at about a 45-degree angle," he said. "I literally couldn't walk straight. It was almost walking just straight to the left."
In the couple of minutes it took his father-in-law to arrive to take him to the hospital, Hader said his condition drastically worsened. By the time they reached the emergency room about a half-hour away, Hader couldn't walk at all and needed a wheelchair.
After a CT scan determined there was no bleeding in his brain, Hader said, a doctor confirmed he was having a stroke and needed to receive a drug known as tissue plasminogen activator, or tPA, which dissolves blood clots.
"I remember sitting there and hearing the doctor yell out that they had 12 minutes to administer the tPA," Hader said. "That's when everything hit home."
He continued: "I was still wanting to be in disbelief. But everything came crashing down, like 'Nope, this is happening'."
His wife, Rebecca, told The Post she was also couldn't believe her husband had a stroke. She said she always told him not to pop his neck.
"I thought it had to be something else," she said. "He's too young. It was too weird. My whole way to the hospital, I was kind of talking myself out of it being a stroke."
Hader said he was transported to Mercy Hospital where he remained in the intensive care unit for several days before being released to a rehabilitation center.
"I was terrified," Rebecca Hader said. "He says he was never worried he was going to die. I did all the worrying that he was going to die."
Not only did Hader survive, but with help from physical therapy, he was on his feet and walking within a matter of weeks.
"For the last two weeks or so, I've been able to help around the house a lot more, doing regular chores or helping out with taking care of our 1-year-old and 5-year-old," he said. "Before that, I was fairly useless."
Hader said that although he didn't lose any cognitive or speech abilities, he still has balance issues, difficulty controlling his left arm, and a lack of sensation in his right arm and leg, among other lingering symptoms.
Nakagawa said Hader's situation could have been much worse.
"They're actually very deadly," Nakagawa said of the type of stroke Hader experienced.
The vertebral arteries in the neck join in the brain to become the basilar artery, which serves the critical role of supplying blood to the brain stem, Nakagawa said.
"The brain stem is the heart and soul of the brain," he said. "Without it, our brain just doesn't work."
If a tear in the vertebral artery impacts the basilar artery, Nakagawa said the stroke can be fatal, cause a coma or leave a person in a permanent vegetative state.
In 2016, 34-year-old model Katie May died from a stroke after going to the chiropractor for a pinched nerve in her neck, CBS News reported. An autopsy found that May's vertebral artery tore as a result of a "neck manipulation," according to HuffPost.
Hader said he only found out how dire his situation could have been after visiting a vascular specialist a few weeks ago.
"He put up his fingers real close together and he was like, 'You were this close to a coma,' " Hader said.
Both the Haders said they never knew neck-cracking could cause a stroke. Nakagawa said he's come across a few cases, but noted that it is a rare occurrence.
Experts in the stroke community still do not know why some people's arteries tear while others don't, but they "have a hunch" that it may have something to do with the integrity of the blood vessels' walls differing from person to person, he said.
According to Nakagawa, "99.9 percent of the time you pop your neck and it's fine."
Hader, however, said his days of neck-popping are over.
"I still wake up every once in a while with the urge, and I have to stop myself," he said. "It's still a struggle, but I definitely don't want to pop my neck anymore."