Have mercy, Uncle Jesse! John Stamos bared (nearly) all in a black-and-white mirror selfie he shared on Instagram Wednesday as he celebrated turning 63. The “Full House” star gave fans an eyeful in the shirtless snap, seemingly wearing nothing below the waist and captioning it simply, “63.” Stamos appeared to have just gotten out of the shower, his wet hair slicked back as he posed in front of the bathroom mirror. The actor’s famous friends were quick to fill the comments with birthday wishes — and plenty of reactions to the cheeky photo. Kelly Rizzo, the wife of the late Bob Saget, was notably among those to weigh in, writing, “All I…
