NORTH MUSKEGON, Mich. (WOOD) – A nasty note left for the mother of a boy with autism has led to some unforgettable acts of kindness – and the biggest surprise is yet to come.

“Buy that kid a muzzle!!” said the note left by a stranger on top of Brittany Miller’s shopping cart as her 6-year-old son, Grandy, rode the pony at Meijer last August.

“It was kind of disheartening I would say, and a little shocking and I was mad originally,” Miller said.

Grandy’s mom says he has the splinter-cell savant form of autism and once he becomes fixated with a topic, he learns anything and everything there is to know about that topic.

When he was 3 years old, he became fixated on shapes. Now as a 6-year-old, it’s fire alarms. He was even a fire alarm this year for Halloween.

The day his mother received the rude note at the grocery store he was making a fire alarm noise, something he does to keep himself calm.

Their story went viral after Miller reached out to 24 Hour News 8 about what happened.

“It blew up and fire alarm companies sent boxes of fire alarms to us, and Grandy opens them up and he knows every one – make and model numbers – and it was like Christmas for him,” Miller said. “It was within days I was getting emails from other parents saying ‘Thank you for speaking out. Can we send your son a gift, can we send you a gift?’ Then I was getting e-mails and messages from fire alarm companies from around the U.S. I looked online and the story was shared in Hawaii and I’m at work scrolling through yahoo.com and it’s a headline on yahoo.com.”

Out of that moment of meanness came months of kindness.

“It’s been insane, and the kindness has been amazing from it, much more kindness than negativity.”

On March 6, for his 7th birthday, the biggest gift yet will come. Honeywell Company, which makes fire alarms, heard about what happened and is flying Grandy and his mom out to their factory in Connecticut.

“This is going to be something he is going to remember forever,” said Miller.

They will give him a tour and are throwing him a big birthday party.

“That note was a blessing in disguise, I had no idea it was going to turn into all this. But Grandy is the one really benefiting from it and giving him experiences of a lifetime that I would never be able to give him otherwise,” Miller said.