Justin Theroux was shirtless to join his heavily tattooed pal, Scott Campbell, for a walk on the beach in Hawaii yesterday. His girlfriend, Jennifer Aniston, didn't go along for the outing, but the duo has been enjoying themselves around the island for the past week. They arrived in Hawaii in order to attend Christine Taylor's birthday party, but it seems Jen and Justin will stick around to celebrate his 40th on Wednesday. Between their shopping, coffee, and fruit runs, it's evident that they're happy being together. It's even been said that Jennifer and Justin seem "giddy in love" as they show PDA during their tropical excursion.