In his new book, The Commitment: Love, Sex, Marriage, and My Family, syndicated sex columnist Dan Savage relates a road trip during which his 6-year-old son, D.J., having sat in a hot car for hours on a “six-year-old wipe job,” endures a painful case of diaper rash. Blaming himself for not insisting on a bath before bedtime, Savage faces the grim task of dragging a rough motel washcloth across D.J.’s keister as the child yells, “DON’T TOUCH MY BUTT, DADDY! IT HURTS! STOP, DADDY! OW! OW! OW!” After Savage’s boyfriend, Terry, administers antibacterial ointment and D.J. falls back asleep, Savage lies awake waiting for the knock of the Sioux Falls, S.D., police, certain that someone has heard his son’s incriminating cries through the thin walls. No, it’s not about marriage, exactly, but it is about family—and a whole set of worries beyond those suffered by Joe and Jane Parent. Not particularly keen on the idea of marriage for himself, Savage nonetheless explores its origins, meanings, and legitimacy, as well as the many other forms that commitment can take. Savage reads at 7 p.m. at Olsson’s Books & Records, 418 7th St. NW. Free. (202) 638-7610. (Anne Marson)