Rape is no laughing matter to Margaret Cho or to the audience that walked out of one of her performances on Saturday night. Cho, 47, performed at the Stress Factory comedy club in New Brunswick, NJ, on Saturday to a sold-out crowd, but not a happy one. Witnesses tell Page Six that Cho opened her set by talking about Garry Shandling’s death and her own rape instead of telling jokes. “She kept on talking about rape and how bad rape is, and it evidently pissed off a few people in the audience,” an audience member told us. “She really got...