Marketplace's Sarah Gardner sits in as guest host for Tess Vigeland this week as we take a look at the so-called "student-loan debt bomb." Also on the show, bill collectors have found new and disturbing ways to turn a profit. We look at what the government's doing to protect you from "zombie" debt. And, what exactly do Girl Scouts learn by selling those Samoas and Do-Si-Do's? Listen to that and more this week on Marketplace Money.