What it means
のなんのって emphasizes an extreme degree, meaning that something is extraordinarily or unbelievably so. It follows a plain predicate and often conveys the speaker’s strong personal reaction, frequently with a rhetorical or slightly dramatic tone. The expression can stand at the end of a sentence or introduce a consequence that shows how extreme the situation was.
Usage note
のなんのって is a strongly colloquial, emphatic expression and is uncommon in formal writing. It is not a literal list of alternatives; the repeated wording functions as an idiomatic intensifier. A natural polite counterpart is not normally used because the expression itself retains its conversational plain style.
Example sentences
初めての海外出張は不安なのなんのって、空港に着くまで何度もパスポートを確認した。
I was unbelievably anxious about my first overseas business trip, so I checked my passport repeatedly until I arrived at the airport.
昨日の試験は難しいのなんのって、私は制限時間内に最後まで解けなかった。
Yesterday's exam was unbelievably difficult, and I could not solve it to the end within the time limit.