On Sunday, Former Girls Next Door star Holly Madison celebrated daughter Rainbow Aurora Rotella's birthday, who turned 2 on Thursday. Madison took to her Instagram. account to post pictures to honor the birthday girl and pictures from the birthday celebration. She has over 696 thousand followers on the social media platform. On Thursday, Madison posted a throwback Thursday photo of herself and proud dad, Pasquale Rotella, looking down on newborn Rainbow. The star received over 22 thousand likes on the photo, which she captioned with the hashtag "#MoreWristbandsForHospitalThanEDC." From the Sunday birthday party, Madison posted Rainbow's custom made PizzaCat Cake, a popular Internet meme for young children. The former Playboy also shared this image of Rainbow's birthday present, a pink toy car. The toy car, which is parked next to Madison's own pink car, is captioned "Like mother like daughter #pink." This could be the first of many 2nd birthday parties that the Girls Next Door star will be celebrating and sharing on Instagram. In a recent interview with Review Journal, Madison said that she is hoping to give Rainbow siblings.