Big-Lipped Alligator Moment: One comic had Gaston carve a bird call whistle and accidentally summon a strange cross-eyed bird creature, with a long scrawny neck, a big red rounded bill, a leopard-stained round abdomen, unlike any species that actually exists. Fictional animals do pop up in the Spirou comics that are part of the same universe as Gaston's, but these kind of creatures are very out of place in the more grounded Gaston comic.
Common Knowledge: The name of the series is just Gaston, not Gaston Lagaffe.
Crazy Is Cool: Some of Gaston's inventions, like the propeller on the roof of his car that recharges the battery: it starts lifting the roof off, so Prunelle grabs, then the whole roof lifts off and Prunelle is sent on a long flight, ending because of, in Gaston's words, "a stupidly-placed wall".
Diagnosed by the Audience: Gaston is sometimes perceived by readers as autistic, due to his lack of social skills (only Jeanne, Jules and Bertrand seems to like him), his passion for music and animals, and his genius when it comes to inventions. Also, he is speculated to be narcoleptic due to the fact that he is capable to fall asleep while standing.
Epileptic Trees: There are two popular theories surrounding the comic's universe:
De Mesmaeker's contracts consist of buying the magazine. If he succeeds, he is cutting funds and will fire everybody. Therefore, Gaston is basically saving the day everytime he ruins the contract-signing. De Mesmaeker is treated like an ominous figure who regularly gets "defeated" by our humble protagonist, so he is the Big Bad in some way.
Mr. Dupuis doesn't fire Gaston because he wants him to deliberately ruin the contract-signing with De Mesmaeker, as he is afraid of his influence.
Growing the Beard: Many people found the comics more funny after Franquin created other recurring characters without the plot focusing on just Gaston and Fantasio, and becoming independant from the regular Spirou cast.
Harsher in Hindsight: Back in the 70s, another Dupuis cartoonist, Seron, infamously took heavy inspiration from Franquin's art to draw his own comic Les Petits Hommes, to the point he filled many sketchbooks with copies of Franquin's character details so he could replicate them better. When Delaf officially reprised the Gaston comic, he basically did the same, building a huge digital database of Franquin's character details so he could replicate them better. Except this time, it was with the blessing of the editor (not so much from Franquin's estate).
In one comic, Fantasio shows Spirou what happens when you whisper things in Gaston's ear while he's sleeping. When you whisper things to Gaston that he likes (eating, sleeping) he smiles, but when you say things he dislikes (working, sorting mail), he frowns. Just as Fantasio gets annoyed at Gaston, Spirou whispers Fantasio's name to him, and he smiles even more than when you mention eating or sleeping (see also Ho Yay). Fantasio is visibly moved, commenting that Gaston is 'a good guy at heart'.
This comic◊ about Gaston sneaking in snowballs to work. It's nice to see Fantasio playfully going along with Gaston's game, which is something that doesn't happen very often.
Another strip has Miss Jeanne being utterly charmed at every single misstep and mistake Gaston commits during a disastrous date. She sees the positive side in absolutely everything to the very end of it.
Hilarious in Hindsight: The Other Wiki mention that there's a real-life businessman named De Mesmaeker in Belgium. Needless to say, taking him seriously whenever he has to sign contracts isn't easy.
De Mesmaeker was actually inspired by one of the relatives of Franquin's coworkers, who coincidentally was a businessman. The man took it rather well, to the point of jokingly asking "Where are the contracts ?" while dealing with French clients.
Ho Yay: Just a bit. In one comic, it is revealed that Gaston likes Fantasio even better than sleeping. Another features a gag which, in a way, sets them up as a couple — Gaston swallows the prize inside a box of candy and has to go to the hospital. When the prize is retrieved, a nurse cheerily tells Fantasio, who is waiting worriedly in the hallway, "It's an airplane!" And then there's a comic in which Gaston surprises Fantasio by throwing paper confetti snippets on him for his birthday. He explains that it's a tradition Americans do for the people they love.
Nightmare Fuel: The dream sequence that serves as awareness to Amnesty International, where the art shifts to Franquin's Idées Noires style where we see Gaston tortured, Miss Jeanne raped in front of him and Gaston wakes up before being executed. And as Gaston points out after waking up, that nightmare happens to real people in some part of the world at this very moment.
Overshadowed by Controversy: The most famous thing about the newest album Return of Lagaffe is all the controversy surrounding the morality of its existence, the ethics of reprising the series despite Franquin's passing and wishes, and the legal battle with his daughter who tried to stop it from being published.
Unintentional Period Piece: The comic had most of its famous run from The '60s to The '70s, and it shows. It is seen in a lot of the fashion, hairstyles, use of old landline rotary phones, comic magazines still a thriving business, a Pong machine seen as a hot video game... Franquin himself said that Gaston was a true product of his times, and that he would be a homeless bum in the 90s. When the comic was made into an animated series in the late 2000s, the setting was specified as being from older times by Prunelle's narration, and the planned Delaf new book keeps the 70s vintage setting.
A series of Product Placement comics promote the Orange Piedbœuf soft drink, that has long been discontinued since (the Piedbœuf company now only makes beer).
The 1981 Movie:
They Changed It, Now It Sucks!: It can be difficult for a fan of the comic to be investigated in the movie considering the Adaptation Name Change, something that was unfortunately enforced by Franquin himself.
Values Dissonance: Pénélope (the Jeanne stand-in), after failing to woo G (the Gaston stand-in) too many times, turns towards the camera and says "Apart from raping him, I don't see what else I can do!". It's already controversial to have a rape joke in a mostly family-friendly adaptation, but decades later, these type of jokes are considered even more unacceptable.
◊ about Gaston sneaking in snowballs to work. It's nice to see Fantasio playfully going along with Gaston's game, which is something that doesn't happen very often.
