Dat Boi is a piece of absurdist humor using an image of a frog on a unicycle the frog is placed in historical, fantasy, or futuristic environments, and the only joke is the strangeness and specificity of him being sighted by, say, Legolas of Lord of the Rings. The big milestone of this newer, meme-influenced use is something called the Dat Boi meme. On the other hand, r/bois was genuinely the first place I felt like I could be accepted for being a gender nonconforming AFAB person who likes being called a boy. In some ways it’s good that gender lines are less important, and of course things shift definition over the years (in terms of the meme use).