Does Instagram girl Katiesonier have the best ass on Instagram? She must have, surely. Camsoda just shared this clip and I must admit I’m now a follower of Katiesonier. I love girls that go above and beyond to keep their ass in tight shape and Katiesonier certainly does that. Just check out her routine and notice how she makes sure she wears the tightest pair of shorts possible. She knows what she’s doing here. Doing the splits every way possible and some ways I thought were impossible fitness girl Katiesonier shows us in this fitness video why she must have the best ass on Instagram.