Actress Kristen Johnston is stripping down for a new PETA anti-cruelty ad. Johnston is to appear nude on horseback, replicating the infamous Lady Godiva personality, as part of PETA’s campaign to stop New York City’s use of horse-drawn carriages. The ad is aimed at tourists heading for Central Park for the holidays who are tempted to take a carriage ride. Johnston says, “I was blown away by how these horses live, or actually I should say, don’t live. The horses go from this horrible job, where they’re pulling people through the streets of Manhattan all day, to this tiny jail cell in this building that’s like a cramped parking garage….