Used in a situation where you haven't done anything cool or unique, and your day was as boring as ever; but it also can be used in awesome situations, like when your buddy Person 1 sees you parachuting off of the 2nd floor.
TL;DR: Synonymous with "same shit, different day".
Person 1: So, how was your day?
Person 2: Just another day at the office.
Sam: Jesus, they worked you over good. You all right?
Nathan: Just another day at the office.
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)