While his gladiator gear in Thor: Ragnarok is inspired by “Planet Hulk,” the outfit Hulk wears while he’s just hanging out with the “Lord of Thunder” on his downtime is pulled from a much different but still popular Hulk story.
When Marvel created its Ultimate line of comics, the Ultimate version of the Hulk was much darker than what Marvel fans were used to. Among other things, the Ultimate Hulk is a mass murderer and a cannibal. In 2005’s Ultimates 2 #3, Bruce Banner is punished for his crimes by being drugged, left unconscious on the deck of an aircraft carrier, and nuked. Of course, he survives.
In 2006, Lost co-creator Damon Lindelof and artist Leinil Francis Yu paired up for the miniseries Ultimate Wolverine vs. Hulk, in which Nick Fury discovers the Hulk is alive and sends Wolverine to kill him. The mutant tracks the Hulk down to Tibet, where the man-monster has taken over a monastery and pressed the nearby town’s women into service in his private harem. The clothes Logan finds him in are identical to what the Hulk wears in Thor: Ragnarok before finally turning back to Bruce Banner.
By the way, the miniseries is also known for the grisly and iconic image of the Hulk ripping Wolverine in half — a moment 2018’s Deadpool 2 pays tribute to when Juggernaut gives Wade Wilson similar treatment.