Pop star Britney Spears has bought her new boyfriend a horse for his birthday. The 33-year-old singer, who celebrated Christmas with her writer-producer beau Charlie Ebersol and her children last week, splashed out on a dark brown steed for his recent 32nd birthday and also purchased a light brown pony for herself.The Perfume hitmaker shared photographs of them riding their new pets around a stable on Twitter. “Birthday horses for my birthday boy,†she tweeted. She also presented him with a huge cake covered in romantic photographs of them together, in addition to images of other couples.