The Pitman sisters are totally sliving! TikTok sensations Hasley, Hope and Halle Pitman recently had the opportunity to work with Paris Hilton to promote the socialite’s new song “BBA” — and they were completely impressed with how kind and down-to-earth she was, the viral siblings revealed during an exclusive chat with OK! at the end of September. “That was a really cool experience,” Hope, 21, tells us. “We’ve all looked up to her and her fashion growing up. She’s the ultimate icon. Being able to work with her and meet her was really cool. She was amazing.” “She was so welcoming and open to co…