A term derived from a lesbian's vagina, often meaning one lesbian is going to perform oral sex or "eat" another woman's vagina. It is implied that a "Sea Bass Special" is a delicious treat that can be "eaten" by one lesbian to another. Yummy?!
Gigi: What on earth is that horrible smell??
Dan: It's the leftover's from when Lindsay and Cindy "went out to dinner." I think they ate the sloppy sea bass special.