Noun? Adjective? Adverb?
Although the cast members of MTV's Jersey Shore got off to a rocky start, they eventually agreed (mostly) that Mike Sorrentino's nickname, “The Situation,” is a noun. They figured it out by falling back on that comforting phrase from grade school (and Schoolhouse Rock!): a noun is a person, place, or thing.
A question some people may find trickier is whether Mike should capitalize “The Situation.” He should, and he does. He noted that his nickname is capitalized when he spelled it while ordering a pizza. All nicknames are capitalized because they are treated like names, which makes them proper nouns.