How did "that's what she said" originate?

Question

Everyone says its from The Office but I thought people said it before.

Answer 1

In Ancient Greece, before Caesar was a salad and when Zeus's beard ruled the skies, the Athens would use it as a battle cry.

"αυτός είναι αυτό που είπε " they would shout at invaders.

This theory, however, has absolutely no evidence supporting it.  

Answer 2

I did a little research and there is a definition for that saying on Urbandictionary.com from May 8th, 2005. The Office premiered May 24th, 2005. Thus, it DID occur before the series premiered. I don't know where it originated though. Sorry!  

Answer 3

This may not help, but I felt like sharing, lol.  I'm 26 now, and I've been using the "that's what she said" line since I was in 5th grade.  I had never heard anyone else use it, and I thought at that time I was the only one who said it or started it.  Then all of  a sudden, years later, EVERYONE is saying it, lol.  I'm not taking credit for it, because my Mom dated a guy who said that where he was from, people said it way back in the late 70's early 80's.

Answer 4

it's an expression that's probably been around for more than a decade, although Michael Scott has popularized it to another level...

I don't think it has a true origin though, just like "don't go there" probably doesn't have a true origin either...