What does it mean?

Despite all the billions spent on corona and her virus there is still a little bit left in the kitty to plant signs on the footpaths around the town. This one says Be open minded. I haven't a clue what it means. Maybe it is meant to be cryptic in a mysterious sort of way. Does it have anything to do with Swingers or is that taking it a bit too far. Anyway only the person who made it up knows what it means or maybe he or she told somebody else but they are keeping it close to their chest.

Anyway Be open minded .