I'll put this in relatively simple terms so that even the intellectually challenged can understand.
Imagine 2 people sitting at a blackjack table. One is your average young person. They have a few bucks in their pocket, they are just getting started. The other person is your sub-prime borrower. The young person has read up and studied the game of blackjack and is going to play perfect basic strategy blackjack, while the sub-prime guy is not playing smart strategy. Throughout the game, the sub-prime guy takes cards or stands at inopportune times, thus messing up the game for the whole table, especially the basic strategy guy. At the end of the night when the basic strategy guy and the sub-prime guy leave the casino broke, someone gives the sub-prime guy his money back. And just to make things stick a little for the basic strategy guy, he's forced to go to the ATM and withdraw cash to cover a portion the sub-prime guys loss.