Y'know, I love how the creators of this show have played around with gender norms here. I know people like to debate whether Marco secretly likes cross-dressing, but for me, that's not the point. The couple of times he's done it, he's totally owned it, and the other characters don't make a big deal about it, either. It gives the impression that there's nothing shameful about dressing like a girl. And honestly, that comes across stronger BECAUSE it's subtle. There's definitely a time for making a point about stuff like this, but it's a pretty natural human reaction to reject what you're told to think. Here, it's shown: in the episodes where Marco's cross-dressed, he's smart and confident and ends up leading a rebellion. And it's not in spite of the cross-dressing, it's actually kind of because of it. At the very least, he wouldn't have been able to do what he did dressed in his everyday clothes. Even then, Marco has some more feminine interests, and while he seems somewhat embarrassed by them sometimes… Well, like, he's a total geek for the boyband Love Sentence, but that actually helps him with the cool girl he's idolized forever. Honestly, I think this show is more progressive than people realize.

According to the internet, it's both a worthless social construct and the most important thing in the universe.