Sticker backs

You know tags?

Well what are those sticket tags that pop up everywhere?

Its like a tag, but drawn on a sticker and stuck to a lamp post or whatever.

Often they are drawn on royal mail special delivery stickers.

Usually they are rubbish and involve little or no skill by the "artist". Though I have seen some good ones.

Seems odd.

I don't get it.

Explain.

Stickers.