VIDEO : Sean Penn Lights Cigarette On 'The Late Show with Stephen Colbert'

Sean Penn made a smoky appearance on "The Late Show with Stephen Colbert" to promote his book. The actor told the host he had taken a sedative "to get to sleep after a red-eye flight" as he lit a cigarette. The two-time Academy Award winner described his novel, "Bob Honey Who Just Do Stuff," as "the conversation once a year with the drunken uncle." Penn proceeded to light another cigarette and Colbert joked that he should consider quitting. Penn said it was "job security for oncologists."