I have a character who one of their primary character quirks is supposed to be that they are very involved in Internet subculture. They're a programmer who spends a lot of their spare time on certain imageboards and social media, and they're a bit of a memelord. The character is young but this quirk is unique to them and not a function of their youth, other characters of the same age are not as involved in Internet subculture as they are.
However, when trying to write this character I've realized that it's very hard to show, not tell, this aspect of their character. Perhaps the biggest issue I've noticed is that the easiest way to show the characters' habits would be through the way they communicate. Because Internet culture colors their worldview it makes sense that they would use that terminology when trying to explain things. However, because of the ever-shifting nature of memes, this would mean that would age super quickly and would come off as breaking suspension of disbelief. It would be the equivalent of a character in a work written in the 70s intended to be seen as a hippie talking about New Age culture: in the modern era they stop looking like a young person and start looking dated. Or they come off as "the author is out of touch and this is how they think the young people behave". Think of a young person unironically using "pwned" in conversation.
I'm deliberately trying to avoid chasing the latest trends to avoid dating my work, but the thing is the Internet and the broad strokes of Internet culture seem like they will be around for some time to come, even if flavor-of-the-month memes wither and die. Given this, how do I portray someone who is involved in Internet culture without dating their character?