Give me an education about this "PIRATE SHIP" method that has been discussed here.

I just signed up and sent out my first package. I'm stoked. I have been losing probably around 50% of my sales due to stupid high shipping cost. I've had a FedEx account for 20 years but I'm not a high volume shipper so I only get like 10% off. Pirate Ship was almost half with UPS.