Paula Abdul celebrated her 50th birthday like she was 20-something at Tao Las Vegas. The former “American Idol” judge was spotted partying with boyfriend John Caprio, “Extra” correspondent Terri Seymour and 30 guests for a dinner before heading to an upper VIP area where she was surprised with a blaze of flashlights followed by a three-tiered cake. Videos played on LED screens as DJ D-Miles spun Abdul’s “Straight Up.” Clubgoers sang along, prompting her to stand and wave to the crowd.