<< Doesn't an adjective describe a noun, so when you say "Something is suck", suck acts as the noun since it is the object the verb "is" is referring to. For it to be an adjective, there would have to be another noun for it to describe >>
In the sentence, Something is suck, "something" is the subject (noun). "Is" is the verb. Because "is" is a linking verb, "suck" is either a predicate adjective (pa) or a predicate nominative (pn). A pa describes the subject, and a pn renames the subject. Pns are always nouns, and pa's are always adjectives. because "suck" is lacking an article, i believe in this usage it would be an adjective - along the lines of "sucky".
Hooray for high school grammar!