Penn & Teller return to barbecue more sacred cows

Cable’s crankiest contrarians return with the third season of “Penn & Teller: Bull!” (9 p.m., Showtime). In their show, with a title unprintable in family newspapers, the witty illusionists take an intellectual blowtorch to popular wisdom, political correctness, fads and trends. In the past they have presented caustic cases against accepted wisdom on secondhand smoke, bottled water and TV mediums. At their best, they make you think. At the very least, they make you laugh. And at their weakest, they are a thousand times more entertaining and provocative than smug network libertarian John Stossel.

Tonight’s season-opening rant tackles the sensitive subject of male circumcision, a medical practice grounded in religious and cultural traditions. Penn & Teller are host to experts on both sides of the issue, and offer a fusillade of seventh-grade-level jokes about the subject at hand.

Penn & Teller also appear (as themselves) on tonight’s Las Vegas-themed episode of “Listen Up” (7:30 p.m., CBS).

  • On a similarly skeptical theme, the National Geographic Channel offers three original episodes of its series “Is It Real?” The first, “Is It Real?: UFO’s” (7 p.m., National Geographic) analyzes “evidence” and eyewitness accounts of “close encounters.” “Is It Real?: Ghosts” (8 p.m.) looks at man’s eternal fixation on spectral phenomena, and my personal favorite, “Is It Real?: Spontaneous Human Combustion” (9 p.m.) looks into stories about people who suddenly burst into flames.

Tonight’s other highlights

  • Couples in need on “Marriage 911” (7 p.m., Fox).
  • Bugs be gone on “Extreme Makeover: Home Edition: How’d They Do That?” (7 p.m., ABC).
  • Ray, Robert and Frank lie about attending therapy on a funny repeat of “Everybody Loves Raymond” (8 p.m., CBS).
  • A lapse in security on “Las Vegas” (8 p.m., NBC).
  • Jack’s methods come under scrutiny, and Chloe is forced to do fieldwork on “24” (8 p.m., Fox).
  • Gang war spills over into a hospital emergency room on “CSI: Miami” (9 p.m., CBS).
  • The wife of a pilot (Chad Lowe) vanishes on “Medium” (9 p.m., NBC).
  • Tiny terrors on “Supernanny” (9 p.m., ABC).