A teenager who wore Halloween fancy dress to promote a new store in the US state of Missouri ended up red-faced after passers-by mistook him for a crazed madman.

According to the Joplin Globe, the unnamed youth had put on a Scream fancy dress costume to generate publicity for the Spirit of Halloween outlet, which has begun selling spooky decorations and other goods in the small town.

However, as he waved at cars and pedestrians in his black cloak, someone got a bit panicked about his mock machete and called the police.

When the cops arrived, the poor employee was ordered to the ground at gunpoint before they realised he was not a psychopath after all.

Indignant shopkeeper Rick Henderson said banners clearly said what the store sold and it was obvious that the boy was part of a publicity stunt.

So if you want to pay homage to the popular Scream franchise, you'd better be careful where you go to in your outfit - you wouldn't want to be mistaken for a real killer this Halloween!