A PETA ad in which the cast keeps its clothes on? It’s true, but the animal-rights group still manages to court controversy with its “Sex Talk” PSA. Apparently inspired by the headline-grabbing Gloucester, Mass., teen pregnancy pact, it shows a mom and dad encouraging their daughter to have sex with anyone and everyone. The no-frills spot is nicely cast. Dad’s whiney, offhand delivery of lines about disposing of unwanted kids (“We can leave ’em in the shelter, dump ’em in the street, whatever”) is priceless. The point comes at the spot’s close: “Parents shouldn’t act this way. Neither should people with dogs and cats. Always spay or neuter.” They mean spay or neuter the dogs and cats, not the kids.