A pun on "Na ttae-neun mariya" ("Back in my day..."). "Na ttae" (my time) sounds like "latte," and the sentence-ending "mariya" sounds like "mal-iya" (it's a horse) — so the phrase reads as both "back in my day" and, absurdly, "it's a latte-horse." Signals an old-timer about to launch into a nostalgic lecture.