The TV show, The Office made that phrase pretty popular, but the first time that the phrase was used was from Wayne's World back in 1992. It is an example of a phrase that is considered a double entendre.
green,and red well thats thats she said. \
green,and red well thats thats she said. \
thats what she said
its small (thats what she said XD)
thats what she said
he has 2 legs and thats how much legs he has and he is small thats what she said
thats not what your mama said last night
Thats what she said. hehe lol
thats what ya mum said
Hour thats what my teacher said at least
because i said so thats why
thats what she said?