Basically, the Avengers all went on vacation and Steve stayed behind to mind the Tower, but Tony’s “vacation” turned out to be him having either built a desert island in the basement men’s room or him having installed a portal to a desert island disguised as a door to the men’s room.
When summoned by Hulk, who saw him going into it earlier, Tony emerges wearing flippers, a pool floaty, and the rightful indignation of someone whose vacation has been interrupted by shape-shifters posing as him who are trying to rob the place.
This one page in Avengers Annual 2013 was kind of a high point in Tony’s comic book characterization in the past five years.