It’s a jab at people who foam at the mouth whenever they get mad that someone is having more fun than they are despite being totally allowed to also do the thing if it weren’t for whatever trauma they’re not dealing with.

I drink my coffee black, too, I just don’t do it because I think I’m a manly-man. It’s actually because I hate the texture of milk or cream and the sugar, to my taste, just exists beside the coffee instead of sweetening it so it’s always awful. I don’t even like coffee that much so it makes no difference either way.