Extremely mild spoilers for Avengers: Endgame ahead.

For all the obsessive secrecy surrounding Avengers: Endgame, there is one dramatic detail we know for sure: At just over three hours, it is the longest Marvel Cinematic Movie of all time.

If just thinking about that run time makes you uncomfortable, that's understandable. Three hours is a long time to go without a single bathroom break, even for a healthy adult who hates drinking water, and no matter how much you're enjoying the movie in question.

So when should you do it?

As someone who's seen the film twice, I can tell you that the honest truth is there's no good time to slip out during Avengers: Endgame. It's a very tightly packed three hours, in that we rarely go more than a minute or two without a big plot development, a significant emotional beat, or just a really awesome bit of fan service.

Your actual best bet, then, is simply to refrain from drinking fluids for a couple hours beforehand, take one last bathroom break during the pre-show trailers, and hope that's enough to keep nature's call at bay.

But even the best-laid plans have a way of going awry, as the Avengers learned to their profound regret at the end of Infinity War. So if you still need to go? Here are your least terrible options for going to the bathroom during Avengers: Endgame.

(Note: While we've tried to be as vague as possible about the content of these scenes, some very minor plot details are mentioned below.)

When Thor discusses the Aether (about 60 minutes in)

At one point in the movie, someone asks Thor to explain the Aether (a.k.a. the Reality Stone, a.k.a. the red one). That's your cue. But don't dilly dally too long — you only have about two minutes before the scene shifts.

As soon as you see the word "Asgard" (about 70 minutes in)

You'll miss some relevant information, but nothing you can't figure out once you get back. Again, come back as soon as you can; you'll have less than five minutes before something Extremely Important occurs.

At the very beginning of the climactic battle (about 130 minutes in)

You'll know it when you see it, and as soon as you see it, run. The entire third act is unmissable, but if you absolutely must miss some of it, it's best to sacrifice the first few minutes. The Big Moments-per-minute ratio is off the charts at this point in the film, and only continues to climb as the scene goes on.

Whenever a character you don't care about is doing a thing

This is a risky strategy, since you have no way of knowing when a character you don't care about that much might run into someone or something you do, or when the scene might shift to a different one entirely. But if you're pretty sure you'd rather gamble on missing a big Hawkeye moment (for example) than skipping even one second of Black Widow screen time ... godspeed.

As soon as the credits roll (about 170 minutes in)

Avengers: Endgame is the rare Marvel movie without a mid- or post-credits scene. Once the film is over, you're free to get out there ahead of all those other suckers still waiting around for one.