Burt Jenner is opening up about Caitlyn Jenner's transition -- and sending out a warning to anyone who wants to hate on his "dad." The reality TV star's oldest son took to Instagram yesterday to share a new photo of Cait, seen with who we believe are Casey Jenner's daughters Francesca and Isabella. The trio look happier than ever as they play with a motorized race car. "So obviously a lot has changed... But thankfully, for me, the most important stuff didn't," Burt, 37, captioned the photo. "My dad still loves toys, fun toys, still likes to go fast, still loves adrenaline and will still whip your ass at... Anything," he continued. "Yup all you haters, my dad will still probably whip your ass at 65 with implants." "Oh 'No'? There were a lot of world class athletes that said the same thing... And lost," he added. "Sure, I believe you,...