LAS VEGAS: Nicole Richie was ‘’crawling on all fours’’ while watching Britney Spears in Las Vegas. The reality star-turned-fashion designer went to support the ‘Perfume’ singer during her residency at Planet Hollywood Resort Tuesday night and enthusiastically danced and sang along to the show. Britney took to her Twitter account to thank the 32-year-old star for going to see her perform. Nicole also posted two photographs on Instagram of her at the show and in one she is seen holding up a Britney Spears’ t-shirt.  Nicole can be seen laughing stood next to the brunette superstar and the pair are surrounded by scantily-clad male dancers.–ES