ladyblueyes:

I remember my grandpa using "back in the day" in the 60's so to my mind, "back in the day" makes me think of the person speaking about 40 years earlier ... so it is kind of funny to me to hear a teen or even a young adult say "back in the day" as if they had REALLY lived.

I don't know where it came from, but it does tickle my funny bone. I mean, I always think something profound is going to follow it ... and then I'm either disappointed or doubled over laughing at the imagery of the speaker in their diapers actually doing what they say they did.

Love it!

goes along with "old school" meaning anything before 2004.