Some women prepare for the stork by nesting. Not Pink. She's spending her remaining days of bun-baking protesting her trademark hue. Specifically, the animal-boosting popster is peeved at Selena Gomez for using pink-colored horses during a video shoot this week. "If there are any animal activists around Malibu at Leo Cabrillo State Beach, there are horses being painted for a stupid music video," Pink tweeted on Thursday. "Shame … Artists should be more aware and responsible for their actions." But Selena and the producers apparently took pains to ensure the animals weren't harmed. "A non-toxic, vegetable-based powder paint was applied via an airbrush and removed with water," her rep explains to People, adding, "An official from the Humane Society was on-set supervising."