Taylor Swift turned 27 Tuesday, and the pop star received social media tributes from her BFFs, including Hadid, Austin Swift and Camila Cabello. But Swift's ex, John Mayer, didn't feel the excitement. Swift and Mayer briefly dated from November 2009 until their tumultuous breakup in February 2010, but their connection was strong enough to allegedly inspire the classic Swift ballad “Dear John.” After deleting his original tweet, which appeared to take a swipe at the Shake It Off birthday-girl, John defended himself,