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.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).
Precedes or follows either a gratuitously disrespectful or honest remark, originated in New York City. Used in similar fashion to "no offense" or "to be honest," interchangeably.
Ya mans is wild buns, respectfully. Respectfully he's washed.
After school, The Modells on Jamaica Ave was active. Respectfully.