The app RunPee buzzes in your pocket when a boring bit is coming up in a film, so you can go to the toilet without missing anything. So whats the safest time to nip out in Casablanca or The Godfather?

Even the corniest summer blockbusters now regularly clock in at two-and-a-half hours. So perhaps it should be no surprise that RunPee, an iPhone app advising film viewers when to step out for a wee, is arunaway success. Start the app when you sit down to watch afilm, and it will buzz in your pocket when a boring bit long enough for a loo break is coming up. The app was launched in 2008 by American developer Dan Florio and has attracted positive testimonials from stars including Rashida Jones and Stephen Fry. Hugh Jackman says it was recommended to him by AnneHathaway.

Updated regularly, RunPee already recommends two wee-appropriate moments each in new releases The Emoji Movie and The Dark Tower (judging by the reviews, you could probably sit them both out in the bathroom in their entirety). Yet even classic movies allow for a quick sprint to the crapper and back.

The Godfather

Just after he has helped to whack his former protg Paulie in the car, capo Peter Clemenza cooks for the Corleone familys made men. If you nip out after the line Take the cannoli, the most you will miss is Clemenzas meatball recipe. To many Godfather fans, this scene is a classic that settles for ever the question of whether to add sugar to tomato sauce. But it was a creation of director (and legendary gourmand) Francis Ford Coppola, and does nothing to advance the plot.

There Will Be Blood

After the long, awe-inspiring blowout sequence in Paul Thomas Andersons masterpiece comes some pee-permitting downtime: fresh oil derricks in operation; Plainview (Daniel Day-Lewis) trying to communicate with his newly deaf son and then asking his sidekick, Hamilton, to find a sign-language teacher. Youll be back in time to watch Day-Lewis beat the crap out of Paul Dano and drag him through the mud by his hair.

Casablanca

Casablanca is a mere 102 minutes, compared with Bloods 158. But if you still cant make it through without a pit-stop, then go at minute 59, just after Ilsa and Laszlo have failed to get a pair of exit visas from fez-sporting kingpin Ferrari. Youll miss a bit of inconsequential business at Ricks bar, albeit with some word-class repartee between Bogey and atwinkly Claude Rains. Be sure to get back before Laszlo comes looking for Ricks hidden letters of transit.

The Shawshank Redemption

Andy has just done a spell in solitary. Red has failed to win freedom at his latest parole board hearing. Its time for a montage. Leave the room when Andy gives Red a harmonica. You will miss Red returning the favour with aMarilyn Monroe poster, followed by a section about Andy securing funding for a prison library and some light banter between the inmates about a copy of The Count of Monte Cristo (another prison break classic) by Alexandra Dumbass.

Star Wars: A New Hope

Our heroes have just escaped the Death Star, and its time to escape your seat and empty your bladder before the final battle. Youll only miss General Dodonna briefing the rebel forces. He explains how to blow up the Death Star, but surely you know all that already: theres a two-metre-wide thermal exhaust port, leading to a shaft that goes directly to the reactor system. A direct hit on the port will start a chain reaction and destroy the station, yada yada yada.

Read more: https://www.theguardian.com/film/shortcuts/2017/aug/09/running-times-when-to-go-for-a-pee-during-classic-movies