“On a scale from one to excruciating pain, how much is this going to hurt?”

Lisa Cerillo asked her doctor about discomfort expectations as she braced herself to be zapped by a fast-pulsing beam around her anus. Ms. Cerillo is a 32-year-old contracts lawyer in Los Angeles who, after years of dating men that deified porn stars, decided to undergo a laser anal bleaching procedure for something that she called, “a chicer-looking butt.”