T-shirts vs. Shirts

If you had written the nickname in full, he would have reacted differently.

Yes, I would have first pointed out that "Lord Black is clearly a dark lord, just like Satan. Moreover, Black Lord is a rather well-known садомазохист, and Satan, according to South Park, is also gay and, interestingly, a садомазохист."

And why "mold"?

Look up criminal slang. It seems to be for that reason, but I don't really remember.