Why is な being used between two nouns?

Question

I was watching a dorama and there was an introduction sentence with な between two nouns, as if the first noun was actually a na-adjective.

「大学３年。彼氏なんてもちろんいない。思い切って私らしくない変身をしたハロウイン…。ハロウインの夜、残り物な私。」

That last sentence was actually written in the screen, so it's not even about being able to distinguish の of な. Is that a typo or a different use of な?

Answer 1

残り物の私 is the standard way to say this. 残り物な私 is not a typo, but a nonstandard yet somewhat humorous way of saying the same thing. I don't think there is a name for this rhetorical technique where an ordinary noun is temporarily employed as a na-adjective, but it's a tactic you'll occasionally see in creative writing. Essentially, this is done to make a phrase sound informal, interesting and/or humorous by using words in a slightly unconventional way.

Similar examples used in titles:

• ボードゲームな夜
  ^{(ボードゲームの夜 is more "standard", but it's uninteresting)}
• クレオパトラな女たち
  ^{("Cleopatraic Women"(?) クレオパトラの女たち would mean something totally different)}
• シュガーな俺
  ^{(This title is intentionally made to be puzzling, but those who read it would notice some unique meaning is hidden)}

Sometimes, employing a noun (or no-adjective) as a na-adjective can also evoke some derived meaning. For example, see ピンクの vs ピンクな and 無垢の vs 無垢な.

Answer 2

Fairly obviously this is the な form of the copula, the writer treating 残り物 as a 形容動詞. What nuance that brings to the utterance only the native speakers will be able to tell you.