A time in one's life looked back upon with great fondness. Usually invokes a memory of a particularly memorable or traumatic incident.
Back in the day, we used to get drunk and cruise the city.

Back in the day, my dad had a mullet.

Back in the day, _________ was a lot cooler than now.
by JenThe80'sFan May 24, 2004
Get a back in the day mug for your girlfriend Jovana.
Referring to a time period previous to the present, usually recalled with a somewhat blissful vision.
Back in the day, I remember those good times we used to have hanging out at Lyon's.
by brainz November 07, 2001
Get a back in the day mug for your barber Bob.
something from the past, sometimes from one's younger years, or the beginning of something.
"I used to play some ball back in the day."
"That team was actually good back in the day."
by Brit October 04, 2003
Get a back in the day mug for your bunkmate Larisa.
Wang: Back in the day we used to eat wood.
Chong: No you idiot, that was a thursday. you dumbass.
by ice up da cornhole April 12, 2007
Get a back in the day mug for your barber José.
A colloquialism used to describe a point in time, specific or otherwise
Person A: I found some old records in an antique store the other day; made from vinyl and everything.
Person B: What are records?
Person A: They're how people listened to music back in the day before CDs and radios.
by Ryan Clark Jr. September 23, 2017
Get a back in the day mug for your girlfriend Yasemin.
Completely meaningless phrase which has gained mysterious global popularity. It means "Once, I..." or "I used to..." but is uglier and lazier. Similar to the equally meaningless "at the end of the day..." popularised by English soccer stars.
Back in the day, I used to be younger.

I was a child once, back in the day.

by hunthill August 16, 2006
Get a back in the day mug for your barber Günter.