Jennifer Aniston paid a gushing tribute to someone very special on Friday with a heartfelt happy birthday post.The Friends star, 51, had an outpouring of love for one of her male friends and boldly called him sexy!MORE: Jennifer Aniston shows support for Chelsea Handler's bikini body But the man on the end of her adoration was none other than her longtime pal - and very happily married - Jimmy Kimmel, 53, dashing fans' hopes of a new romance for Jennifer.WATCH: Jennifer Aniston and Brad Pitt