A more severe/extreme version of
Down Bad or Down Horrendous. The term is usually used to describe someone who hasn't had a significant other or a hookup in a very long
time and is just downright desperate for
literally anyone at this point so that they can experience love, lust, affection, and everything in between.
Marie: "Hey, isn't this boy cute?" *Shows picture of HIDEOUS boy*
Stacie: *Throws up* "Ew
Marie! You are definitely down catastrophic!"
Moral of the story is,
don't get to a point where you're down catastrophic.