Prime time for a potty break during a movie? There’s an app for that.

I’m at “The Hunger Games: Catching Fire” the other day, cradling a drink the size of Marlon Brando, 40 corpulent ounces of sugar water priced higher than Texas crude. If this thing capsizes, I may well drown.

This 40-ounce Coke is considered a “medium.” Presumably, the next size up is Lake Powell.

Why so much soft drink? It’s part of my test of a quirky movie app that tells you the best time to take a bathroom break. In this age of ever-longer movies (and ever-smaller bladders), it seems the perfect fit for me.

What you do is download the app, click when the movie begins, and your phone will vibrate during predetermined slow spots, indicating restroom opportunities.

PHOTOS: Holiday movie sneaks 2013

While you’re in the loo, the app fills you in on what you’re missing. Then back to your seat you go, and the whole sweet cycle begins again.

Slurp, slurp, vibrate, flush.

If you’ve seen “Catching Fire,” you know that slow spots are rare. It’s a breathless piece of cinema, and this Jennifer Lawrence continues to amaze. Generally, the depth of my observations carries about the same gravitas as subway scrawls. But I’ve fallen for Jennifer Lawrence and I can’t get up. She might be the most amazing American prodigy since Mozart.

(Where else do you find that kind of historical reach?)

Anyway, back to this app, another significant signpost in human history.

It was created by an Arizona software developer after sitting through the Peter Jackson remake of “King Kong.” Three hours in and the big ape was still chewing scenery. The developer, Dan Flores, was in a near-fetal position waiting for the end of the movie.

“It’s not just about can you sit through a movie,” Flores explains. “But can you enjoy it?”

So he created this RunPee.com. At first, he gave the app away, but a year ago started charging 99 cents. He says he’s seen about 250,000 total downloads.

BEST MOVIES OF 2013: Turan | Sharkey | Olsen

Providing content is a family affair, with his mom, sister and niece deploying each weekend to help him check out new releases, picking the appropriate break times, and writing up the synopses of what happens during potential bathroom breaks. L.A.-based critic Shanee Edwards also contributes.

Flores says picking break times has taught him a lot about movies. Even if it’s not a genre he prefers, he can spot a good storyteller and a director who knows what he or she is doing.

“It’s super hard to find [break times] in good, well-made movies,” he says.

In the app, potential restroom breaks are signaled by the vibrating phone and a screen countdown. There is also a dialogue cue that confirms the breaks, typically about four minutes long.

For example, in “Catching Fire” when the peacekeeper commander says, “OK, but next time it’s the firing squad,” it’s your signal for the first break. The app offers a total of five potential breaks in the movie, and there’s a short analysis at the beginning that recommends the best one.

In Flores’ estimation, that preferred break comes 90 minutes into “Catching Fire,” after Katniss clips the dome’s force field with an arrow. As he notes, there’s no action or key character development during that period. Plus, at five minutes, it offers the longest break.

PHOTOS: Box office top 10 of 2013

Does the movie house etiquette of a flaring phone screen trouble you? It did me, and I tested it during a lightly attended matinee, so as not to bother fellow moviegoers, for whom I couldn’t care less. But still....

In such conditions, discreet peeks at the phone are possible, though whether you can be discreet during a sold-out movie remains to be seen. You can also keep the phone in your pocket, and rely on the vibrating cues to tell you when to make your bathroom run. Which is what I mostly ended up doing, through 40 very-fluid ounces of multiplex soda.

So that solves one problem. Now if they could just make shorter movies again....

chris.erskine@latimes.com

twitter.com/erskinetimes