Meaning of "Feminism is BAY"

In S05E04 of BoJack Horseman TV-series BoJack appeared in a "Feminism is BAY" t-shirt, emphasizing his pro-feminist attitude. I don't know for sure whether it's the creators of the show who came up with that idea or it's a well-known phrase. Such t-shirts are now available for purchase online. Could someone explain the original meaning of the phrase, if there is one? Apart from bay being a horse-themed play of words.

Solution 1:

"Bay" (also "bae") is a slang term that is a shortened form of "baby", a term of endearment as in, "She's my baby." Over time, the term also came to be used to express that something is cool. This second use isn't very popular or accepted in popular culture, though, so BoJack Horseman (because it is comedy) is using the term presumably because the writers wanted to show that BoJack doesn't even understand feminism (since "bay" in it's more popular context almost always refers to a woman by her relationship to a man).