Back In The Day Meaning

(temporal location, idiomatic, informal) In the distant past; especially, at a time fondly remembered.

Example: 1995 April 8, Havelock Nelson quoting Jemini, “Mercury Debut Rapper Jemini Proudly Displays All His ‘Scars’”[1], Billboard, volume 107, number 14, Nielsen Business Media, ISSN 0006-2510, page 18:
  I wanted to do a song that epitomizes the feeling and vibe from back in the day while still being current.
2005 April 5, Joe Lapointe, “COLLEGE BASKETBALL; North Carolina's Leader Does His Father Proud”[2], The New York Times, retrieved on 2010-06-27:
  Sean May played like they did back in the day, kind of like 29 long years ago, when his father led Indiana to a national championship in 1976.
2009, Everett Peacock, The Parrot Talks in Chocolate[3], Everett Peacock, ISBN 9781442160477, page 31:
  Ah, back in the day. After stumbling out of the service entrance, and wandering to the beach to swim off our buzz, we would barefoot it down the beach to the Outrigger, where Mr. Don would sometimes do a cameo at the microphone.