Avengers: Infinity War is currently in theaters and breaking box office records left and right so I don't know how you've gone this long without seeing it and avoiding spoilers. Even some of the cast, like Mark Ruffalo and Tom Holland, who are notorious for leaking spoilers, have been strategically paired up to prevent leaking spoilers in interview.
Last year Mark Ruffalo accidentally leaked the first 10 minutes of Thor: Ragnarok when he left his Instagram Live on and in his phone and apparently he spoiled Infinity War and no one has noticed until now.
***WARNING SPOILERS FOR AVENGERS: INFINITY WAR FOLLOW"""
In an interview with Good Morning America, Ruffalo and Don Cheadle were being interviewed at Disney's D23 Expo for Thor: Ragnarok and Infinity War where Ruffalo spoils the end of Thor and then goes on to spoil part of Infinity War.
I won't write what he said, but know that he instantly regretted saying it and that Don Cheadle looked so pissed off at him after he said it. The choice is up to you if you want to be spoiled below.