In an apparent protest of statewide mask mandates, a merry band of pranksters placed signs on the exterior of Libby businesses informing passersby that “tin foil hats must be worn” inside.

Libby Chief of Police Scott Kessel said his department was investigating the signs, which appear to have been posted late in the evening Dec. 13. While the individuals who conducted the pranks didn’t damage any property, Kessel said they could be charged with criminal mischief.

The morning after the tricksters passed through town, Kessel said officers had acquired video footage from three different locations. Ironically, the miscreants were wearing face coverings to conceal their identity when posting their anti-mask satire.

Kessel noted that whoever created the posters must have invested a good deal of time and money into the project. The signs, made of glossy printer paper, seem to have been produced using a laser printer.

“I guess everyone needs a hobby,” Kessel said.

As far as Kessel was aware, the signs were only posted in the Libby area.

Playing off of the sign’s satirical message, some businesses have organized events with a tin foil hat theme.

The charge of criminal mischief carries a fine not to exceed $1,500 and or a term of imprisonment in the county jail not to exceed six months, according to Montana Code Annotated.