The 39-year-old actor wasn't prepared for how ''emotional'' the movie made him feel and the 35-year-old actress feared he didn't like the film when he suddenly fled his seat - but he was looking for something to soak up his tears.
Speaking on 'The Ellen DeGeneres Show' on Wednesday (28.11.18), he said: ''I tried to prepare them for how emotional it is. The first time I ever saw it, they give you a tissue box in the screening room. I was like, 'Oh that's very nice, I don't have a cold.'
''And they started screening the movie and 25 minutes into the movie I stood up and went to the back of the room and Emily said, 'Do you not like it? I've never seen this happen.'
''I was pushing through all of the muffins and bagels that were in the back looking for napkins.
''I was like, 'I need anything to stop this crying!' I was crying so much I blew through the tissue box in 20 minutes, had to go to the napkins, and then when I ran out of napkins it was all sweater.''
Emily portrays the magical nanny - who was originally played by Dame Julie Andrews in 1964 - in the upcoming 'Mary Poppins Returns', and John found the film to be ''pure joy'' and is a must-see over the festive period.
The actor - who has children Hazel, four, and Violet, two, with his spouse - added: ''It's honestly one of the most beautiful films. It's I think exactly what everybody needs for the holidays. It's pure joy.''
What's new in the music world this week?
Watch three incredible live performances from Discovr.TV.
Don't miss the K-pop titans' return to Europe.
Listen to Alex Bayly performing 'Animal'.
Two weeks ahead of Independent Venue Week, Dry Cleaning made 'Britain's Best Small Venue 2015' (NME) the second port of call on their 2020 tour.
'Leave Home' was released on this day (January 10th) in 1977.
For their last gig of the year, The Libertines came back to their adopted hometown of Margate to finish off their latest tour.
It's the summer of 1967 and the city of Detroit, Michigan is in the midst...
Don and Sally Hollars' family are all grown up and they live alone. They have...
Not the subtlest director working in Hollywood, Michael Bay brings his surging machismo to this...
In this featurette, we get to meet some of the real life heroes 13 Hours:...
Being a security contractor stationed in Benghazi is a job that most people would not...
Benghazi, Libya has become out-of-control, with Islamic extremists terrorising the state with multiple bomb attacks....