Comedy Central's Stephen Colbert is running for president. He's parodying the process — including, now, superPACS — in the same way he has parodied cable news. He's getting plenty of attention, but to really look into his political practical joke, I needed to go upstairs and find Peter Overby, NPR's man on campaign finance. I warned him it would seem like a dumb question, but I needed his help. What, exactly, is a superPAC?