Origin Of That’s What She Said: A History 4
Update February 5th, 2012:
Some time ago, it was brought to our attention that the master of suspense, Alfred Hitchcock himself, used a variation of “That’s What She Said”  in a sound test sequence with actress Anny Ondra for Alfred Hitchcock’s 1929 film “Blackmail. See video below:”
With the enormous success of The Office comes the equal popularity of the shows signature line, “That’s what she said.” I remember the first time I heard Michael Scott deliver this lame pop culture quote but couldn’t for the life of me figure out where I’d heard it before. After informing my roommate
that it was not an original line but not being able to back up my claim, my pursuit of the origins of “That’s what she said” began. I knew Michael Scott loved to quote movies, or take them in as his own, so I was pretty confident that this was the right direction and would definitely be in character. I searched sites all around, big and small, from Facebook (more on that in a bit) to Wikipedia, and no one seems to have an origin for this newly re popularized phrase, but it was featured in the movies Wayne’s World, Rules of Engagement, and Beverly Hills Ninja (Yay Chris Farley!) and the television series “Family Guy” as well as “King of the Hill”. All likely sources for our favorite television boss man Michael Scott. Also I found this bit-o-news about International ‘That’s What She Said’ Day created on Facebook! That’s right, with so many members (over 147,000 including me!) it’s gotta be official! Okay maybe not, but I’m marking February 15th on my calendar official or not. “That’s what she said” May not be an original line from The Office but it has definitely come into its own. That’s what she said. 
Well done sir………..that’s what she said.
it was also on the upright citizens brigade.
The Strokes – “Meet Me In the Bathroom” 2003
Lyric – “Meet Me in the Bathroom, that’s what she said.”
Earliest usage is in the movie ” National lampoons Christmas vacation” uttered by Chevy Chase near the end of the movie when his boss is at their house.