Not so long ago, there was a pretty big rumour that Matt Damon was going to be turning up for a secret cameo in Thor: Ragnarok. Many scoffed, some flat-out rejected it, while an enthusiastic minority just got extremely excited at the prospect. There's too much cynicism in the world as it is, after all.
But now it looks suspiciously like there may have been something in the rumours, as Matt Damon coincidentally turned up on Jimmy Kimmel to unceremoniously crash Chris Hemsworth's interview ahead of the film's release in a few weeks.
Hemsworth was talking the film up with Kimmel and as focus shifted to Mark Ruffalo and Taika Waititi in the Green Room, Damon appeared out of nowhere for a big crowd pop. Shenanigans followed, until Damon ended up on the jumbo screen behind Hemsworth and Kimmel.
Naturally, the "random" appearance adds fuel to the rumours that Damon does indeed have a cameo in the film - which is said to be hilarious. And if the MCU is capable of such big hires for tiny roles, it's just further statement of how huge a brand they're running.