this not in something that you catch yourself at a random point-- this is what that's what she said is used for, just at yourself. This clause is used specifically in a response to someone who just said "that's what she said", as to keep them from saying it more than once.
Jacob: That's what she said.
Josh: That wasn't very good.
Adam: I dunno I kinda liked it-- no "that's what she said" intended.