Nothing captures our collective sense of humor like the idea of Mr. D and Chiron being exes forced to co-parent the entire camp. The sheer chaotic energy of Dionysus showing up to mandatory parent-teacher conferences, complaining about the wine selection, while Chiron tries to maintain a shred of decorum is just too good. It explains so much about their dynamic—the bickering, the passive-aggressive notes left in the Big House, the way Chiron seems eternally exhausted. You just know Dionysus would make all the satyrs call him 'stepdad'.
Another one that always gets me is the headcanon that whenever Percy is bored or nervous, he unconsciously makes water do little tricks. Like, he's sitting in class and a puddle outside starts doing perfect loop-de-loops, or his drink straw starts spinning on its own during a tense conversation. It's such a subtle, character-driven bit of humor that fits his ADHD and his power being an extension of his emotions. The thought of Annabeth catching him doing it and just rolling her eyes is perfect.
Let's not forget the idea that Nico di Angelo absolutely, 100%, has a secret, meticulously organized playlist of emo music from every decade since the 80s on his iPod, and Will Solace found it once and died laughing. Nico would claim it's for 'atmospheric research' or something, but we all know he's belting 'Welcome to the Black Parade' in the shower. The fandom's dedication to Nico's goth-panicked-teenager vibes is one of the most consistently funny things to come out of the community.