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If you're wondering why the nation is laughing at pop singer Jessica Simpson, catch up by watching the "Newlyweds" marathon (6-11 p.m., MTV). It stars Simpson and her husband, Nick Lachey, who also is a pop singer, in a reality series about their life together. Simpson -- who asked with cameras rolling if Chicken of the Sea is canned poultry or tuna -- may not be as dumb as she sounds, now that she has a sitcom deal with ABC.
Those who can take only so much holiday warmth may find that a duo of irreverent magicians provides an antidote with "Penn & amp; Teller" (8 p.m., Showtime). Five "Penn & amp; Teller" episodes will be shown back-to-back.
Jeff Corwin steps aside as host of "King of the Jungle" (8 p.m., Animal Planet) as the winner of the competition takes over for this episode.
"Monster Garage" (9 p.m., Discovery) mixes holiday cheer with lug nuts as home-design guru Christopher Lowell visits garage host Jesse James to decorate a Christmas parade float.
Rick Sebak shares his unique view of the churches, gatherings and displays that separate the Iron City from other places at Christmastime in "Happy Holidays in Pittsburgh" (10 p.m., PBS Channels 45 & amp; 49).