In the lead-up to Avengers: Endgame, one of the more popular fan theories (if we can call it a fan theory) was that Ant-Man could feasibly defeat Thanos by shrinking himself down very small, inserting himself into Thanos' ass, and then expanding to Giant Man size. This is a sentence I just wrote and you just read, and neither of us are the better for it.
Of course, as we all learned when Avengers: Endgame hit theaters back in May, the secret to defeating Thanos didn't involve any butt-related combat; in the end (no pun intended), all it took was Thor's axe, a bit of time travel and Iron Man snapping his fingers one last time to rid the MCU of that big purple douchebag once and for all. And as it turns out, Ant-Man wouldn't have been able to beat Thanos that way, anyway.
In a new interview with Empire, Avengers: Endgame co-writer Christopher Markus completely dismisses the "Ant-Man VS. Thanos' Ass" question, explaining - with what we can only assume was a superhuman level of patience - that Ant-Man would simply not be strong enough to break through the Mad Titan's formidable rectal walls:
“Thanos could take a punch from the Hulk, we've seen that. And it stands to reason his whole body is at least as strong as that. If Ant-Man expanded, he would be simply crushed against the immovable walls of Thanos’ mighty rectum.”
So, there we have it. Another totally brilliant and well-worth-considering fan theory, cruelly dashed on the rocks of reason by a member of the Hollywood elite. Oh, they think they're so smart, don't they, with their produced screenplay credits and their successful careers and their "logic", but I think we all know better. We've run the numbers, and we are certain that if Ant-Man were to just expand rapidly enough, he could almost definitely catch Thanos' rectum unaware. And if he were able to expand to full Giant-Man size within that window of time? Bing, bang, boom. That's the ballgame.
Neither here nor there at this point, I suppose. But wherever you stand on this extremely important issue, you now have an official answer from one of the folks who could've made it happen. Avengers: Endgame is expected to arrive on Blu-ray this August.