Watch Last Vegas for Free: How to Stream the Movie Online at 123Movies. . Aging pals Billy, Paddy, Archie, and Sam have been best friends since childhood. When Billy finally proposes to his much-younger girlfriend, all four friends go to Las Vegas to celebrate the end of Billy's longtime bachelorhood and relive their glory days. However, the four quickly realize that the intervening decades have changed Sin City and tested their friendship in ways they had not imagined.