Big Hero 6 managed to take a silly recurring fist bump gag and pay it off in a surprisingly emotional way. Big Hero 6 is based on a very obscure 1990s Marvel comic series of the same name, though the resulting adaptation is only loosely based on the source material. The movie follows a boy named Hiro (voiced by Titans’ Ryan Potter) who investigates the death of his brother with the aid of an adorable inflatable medical robot called Baymax (Scott Adsit).

Big Hero 6 is set in a hybrid city dubbed San Fransokyo, with Hiro forming together a misfit gang of superheroes to take on a supervillain and solve his brother’s death. Not only was the movie a huge success upon release - grossing over $650 million worldwide - it also nabbed Best Animated Feature at the Academy Awards. Despite having a post-credit scene setting up a potential sequel, Big Hero 7 has yet to come together.

The relationship between Hiro and Baymax forms the emotional core of Big Hero 6, with the latter helping the young boy come to terms with his brother Tadashi’s demise. One key bonding scene has Hiro teaching Baymax how to fist bump, which takes the confused robot a little while to grasp. Hiro makes an explosion sound after giving the robot a fist bump, with Baymax responding with “Ba-la-la-la-la.” This odd reaction was initially rejected by the filmmakers as too odd after voice actor Adsit improvised it, but they later found it fit the scene perfectly.

This joke repeats a couple of times throughout Big Hero 6, including a scene where he gives a butler a fist bump. In the finale, Baymax seemingly sacrifices himself to save the day, which understandably leaves Hiro heartbroken. Towards the end of the movie, Hiro looks at Baymax’s old rocket fist and for old-times sake, gives it a little fist bump, followed by a soft “Ba-la-la-la-la.” It’s a touching moment, but it also helps Hiro realizes the fist is holding Baymax’s health care chip. This allows Hiro to rebuild the robot, who also retains his memories.

It’s not every animated movie that can make a fist bump of all things emotionally resonant, but Big Hero 6 managed to pull it off. While a sequel has yet to be confirmed, the characters and most of the voice cast returned for Big Hero 6: The Series, which debuted in 2016. The show has run for two seasons thus far, with a third on the way.

Next: Will Big Hero 7 Ever Happen? Here’s What We Know