Fox's MADtv is exposing the big mystery behind ABC's Lost the only way it knows how — with a dead-on parody. On Saturday's show, the plane-crash survivors — as channeled by the MADtv troupe — will learn that they've been stranded on Survivor island when they run into special guest star Jeff Probst. In true Lost tradition, the skit will probe Jeff's back story via flashback. Keep your eyes peeled for a cameo by one Colby Donaldson.