"You are not in Kansas any more, you are on Pandora."
But for mega-fans of James Cameron's monster hit Avatar in 2009 (back in IMAX 3D this weekend), the problem came after its near-three hour running time had completed... they weren't on Pandora any more, they had been dropped back down to Earth.
Avatar was a phenomenon, not just another box office behemoth but a movie that dominated the cultural conversation as a new decade dawned.
Read more: Everything we know about Avatar 2
Both its lovers ("It's an awe-inspiring treatise on colonialism!") and its haters ("It's the Smurfs meets Ferngully: The Last Rainforest, but not as fun!") just could not stop talking about it.
The film's financial success, like Cameron's earlier king of the box office, Titanic, relied heavily on repeat viewing: once audiences left Pandora, they were unable to resist booking a return visit.
Fast forward more than a decade, and with a long-awaited sequel finally landing in cinemas at the end of this year, those audiences can relive Avatar all over again.
On 23 September, the original is back in cinemas, rereleased with remastered picture and sound, before the next instalment, Avatar: The Way Of Water — the first of at least three more sequels — arrives in December.
Watch the teaser trailer for Avatar: The Way Of Water
Avatar is already the highest grossing film of all time, largely thanks to a previous rerelease last year in China which pushed it past the $2.8bn mark, and past Avengers: Endgame.
So is Pandora withdrawal about to happen all over again?
Read more: James Cameron hits back at Avatar critics
That feeling of being transported to an immersive other world isn't just something that superfans dream up — it's actively promoted in the franchise's marketing.
In January 2020, when new concept artwork from the sequels was unveiled, the official Avatar Twitter accounted posted: "In the Avatar sequels, you won’t just return to Pandora — you’ll explore new parts of the world."
Exactly 10 years earlier, in January 2010, CNN reported how audiences were experiencing what it called "Avatar blues" after the film's release.
Read more: Has James Cameron spoiled the end of Avatar?
One online Avatar fan forum at the time contained a thread called, "Ways to cope with the depression of the dream of Pandora being intangible".
It received hundreds of posts from fans who said they were depressed that Pandora wasn't real.
The site's administrator, Philippe Baghdassarian, said: "I wasn't depressed myself. In fact the movie made me happy.
"But I can understand why it made people depressed. The movie was so beautiful and it showed something we don't have here on Earth. I think people saw we could be living in a completely different world and that caused them to be depressed."
Some of those posting said they were upset because Pandora would always remain a place of fiction. Others said the film made them depressed, not because they couldn't be part of the world it depicted, but because it highlighted how we humans in the real world exploit our natural resources.
There is an interesting battle at the heart of Cameron's depiction of the moon of Pandora, whose indigenous humanoid population — the Na'vi — are threatened by human colonisers trying to mine a mineral called Unobtanium (subtlety has never been Cameron's calling card).
On the one hand, Avatar portrays Pandora as an otherworldly idyll, coming down with lush colours and floating islands. Those trying to exploit Pandora see it rather differently.
The head of mining security, Colonel Miles Quaritch, played by Stephen Lang, is the one behind the movie's famous Wizard Of Oz-riffing "Kansas" speech. What is often overlooked is that he follows up with: "If there is a hell, you might wanna go there for some R&R after a tour on Pandora."
It's not difficult to guess which vision of Pandora — Cameron's or Quaritch's — is the one in which audiences longed to be embedded.
At the time of Avatar's release, there was no way to come close to the experience of being "inside" the movie. But by May 2017, fans could do the next best thing: go to a Disney theme park.
Pandora - The World of Avatar, part of Walt Disney World Resort in Florida, opened five years ago, and offers visitors the chance to participate in the Flight of Passage and Na'vi River Journey rides.
Later that year, Disney announced its acquisition of 20th Century Fox, the studio responsible for Avatar.
Perhaps Pandora withdrawal may not be as much of a factor in the wake of the release of Avatar: The Way Of Water, in a modern movie world where every successful film franchise is only a short step away from becoming a theme park ride.
Avatar returns to IMAX 3D and cinemas from 23 September, while Avatar: Way of the Water hits cinemas on 16 December.
Watch: Disney's theme park ride, Pandora - The World of Avatar