We all know that a teal pumpkin at a home on Halloween means allergen-free treats, but what does it mean when someone is trick or treating with a blue pumpkin?

You may have seen the post floating around Facebook. It says that when you see someone trick or treating with a blue pumpkin, it's a sign to let you know that person has autism. It sounds like a good idea, but is it actually a widely recognized symbol?

It turns out, it's not - but it could be.

According to Snopes.com, at one point there was a parent who let her neighbors know that here child, who is autistic, would be carrying a blue pumpkin - just so they would be aware, and be sensitive to his needs. MSN.com reports that parent is Alicia Plumer. "Trick or Treat....the BLUE BUCKET...if you see someone who appears to be an adult dressed up to trick or treat this year carrying this blue bucket, he’s our son! His name is BJ & he is autistic. While he has the body of a 21 year old, he loves Halloween. Please help us keep his spirit alive & happy. So when you see the blue bucket share a piece of candy. Spread awareness! These precious people are not 'too big' to trick or treat," she explained in a social media post.

But, unlike the teal pumpkin, there is no organized effort to make the blue pumpkin a symbol to signify that a trick or treater is on the autism spectrum.

Maybe in the future parents will decide this is an important effort to get behind. Until then, be aware that whether you're the parent of a child with autism, or an individual handing out candy, the blue pumpkin is just that: a blue pumpkin.