When: Fri., 10 pm ET, on HBO
What: Maher's 12th season featured CelebStoners Willie Nelson, Seth Rogen and Kal Penn, whom he asked to deliver a message about marijuana to his former boss, Pres. Obama. In another episode, Maher divulged his undergrad drug-dealing secrets ("selling pot allowed me to get through college"). His current season is his 13th. The ultra-liberal host never misses a chance to stump for weed.