Actually, defacing things you don't own is wrong. Let's find another way.

Think it through, someone has to come by afterward and clean up the sticky mess from your adhesive. They scrape away and curse under their breath about the "bitcoin people" who did this. It hurts rather than helps.

Imagine if someone stuck their favorite sticker on your windshield. Would that be okay? Sharing and showing stickers is fine, promoting pasting them on others' property or public property is not. Find a better way.