I lowkey hope these stories are fake or it's all the same guy
I noticed increased frequency of posts in places like r/rpghorrorstories, that describe a situation where the player brings a tiny veiled or just a shameless copy of a popular fictional character - Sokka, Scanlan, John Snow, Walter White - except "more based" or "less of a cuck". What follows is a story of the player doing some horrible manosphere shit.
I know that a lot of posts on places like these are fake, but in this case I kinda hope they are. Or that it's all the same guys at different tables. Either is more comforting that an idea of an army of incels trying to rp their extremely toxic fanfiction on the table.
Based is one that, as another user said, could go either way. Its original use is very alt-right, but today I personally probably see it used more in support of leftist ideals.
Cuck certainly is much more of a red flag. I have seen it used ironically by people whom I have reason to respect, but it's far more likely to be the source of some serious questions.
I posted this under another comment but it was originally from a rapper Lil B the Based God
"Based means being yourself. Not being scared of what people think about you. Not being afraid to do what you wanna do. Being positive. When I was younger, based was a negative term that meant like dopehead, or basehead. People used to make fun of me. They was like, 'You’re based.' They’d use it as a negative. And what I did was turn that negative into a positive. I started embracing it like, 'Yeah, I’m based.' I made it mine. I embedded it in my head. Based is positive."
So ironically, I came here immediately after closing down Twitter, where I saw this in one of the trending tags. Transphobic rather than alt-right, but the overlap between those two groups is nearly 100%. This kind of thing is apparently (based on other replies) not how the term originated, but it's certainly how the term came to be popularly known.