In Poland, OLX (basically equivalent eBay) commonly has promotional campaigns, where you can buy something from a select category with 1 PLN shipping to box machine (around $0.30).

So people figured out, that you can abuse it to send anything to anyone in the country. Just create a fake listing for 1 PLN, let the receiver "buy" it (there is some extra service fee, but like $1) and there you go - probably the cheapest shipping possible, much cheaper than regular ~$5-7 box machine package.