A decade ago I was getting junk mail from citibank. They were offering loans. It was just on the news how these loans were very expensive, basically bankrupting people and hoping social security would pick up the tab.

It contains a reply enveloppe, so I put all their junk in there, write 'stop sending me junk' on it, and drop it in the postal box. Basically, anything costing them money is fine. Next week, same junk, same reply.

Then I start putting all kindd of other junk mail in the enveloppe. They wont give up.

We're rebuilding the house, so I fill a box with stone dirt, tape the reply enveloppe on top, and send it back. They actually phone me with a complaint, and demand I stop it. I politely decline, ask how they see themselves as good guys while pushing people in poverty, and congratulate them with their box. Presumably that got trough, as I never receive anything from citibank again.