What were you thinking “Saturday Night Live”? That’s what a lot of fans — and mothers of addicts — are saying after a sketch on this weekend’s show featured a fake drug commercial for “Heroin AM,” an option for people “who want to use heroin” but also “get stuff done.”In the commercial, actress Julia Louis-Dreyfus plays a school-bus-driving mama who says she can “get jacked on scag, and then get ...