The average Marvel movie has at least four clap-worthy moments: the first time a hero suits up, the best one-liner, when good triumphs over evil, and when Stan Lee shows up. But in my experience — which includes a 31-hour Infinity War marathon — only one of these moments is guaranteed to get a reaction every time. From the dull, dour The Incredible Hulk to the carefree world of Spider-Man: Homecoming, Stan Lee’s cameos killed every time.

Lee helped create heroes like Spider-Man, Iron Man, and Thor. He makes frequent cameos in films and shows featuring his work, but the Marvel Cinematic Universe movies have turned his cameos into an institution, playing on the enthused, beloved-uncle persona he’s always had in Marvel’s comics. Since Marvel kicked off its long march to Avengers: Infinity War back in 2008 with Iron Man, Lee has appeared in every single film connected to the storyline. Even though his appearance is a given in modern Marvel films, fans at my marathon couldn’t get enough of him, whether he popped up during the kickoff film, or at 3AM, when delirious viewers were barreling through Avengers: Age of Ultron. He’s had a hard time of it lately in the news, with a sexual harassment lawsuit levied against him, and an elder-abuse lawsuit he’s filed against a former manager, but in the films, at least, he’s just a reliably perky in-joke, a shared wink-wink moment between fans and filmmakers.

Lee’s cameos are an obvious homage to his influence and impact on comics, but they’re also a treat for viewers. He lends levity to a film, whether he’s trying to drag Thor’s hammer away with a truck or doubting the existence of superheroes at all. It might be a distracting moment of wall-breaking if it weren’t done in such good fun. As I settled in to watch Infinity War at the end of the MCU marathon, one fan stood in front of my theater with a simple plea: we’d all been cheering every time Stan Lee has appeared, but those were during movies we’d likely already seen. For Infinity War, could everyone just quiet down so we could hear his line? It was an admirable request, but fans couldn’t help themselves. When Lee inevitably appeared in the film, the whole theater shook with celebration.

The audience is crucial to the movie theater experience. A good crowd adds energy, excitement, and even camaraderie. For Marvel movies — an exercise in fan service — sharing the experience is even more important. An in-joke is only good when you have someone to share it with, and Stan Lee’s appearances are referential humor at its most accessible. You only need to recognize him for who he is.