While TWSS isn't used exclusively on the Lounge, it is used frequently enough to warrant epistemological study.

From online sources:

"In America, the earliest documented case of the phrase appears in a 1975 episode of Saturday Night Live. In particular, it was Chevy Chase using the joke during "Weekend Update" on the show's first season. It was kept in popular use on Saturday Night Live through repeated uses in "Wayne's World" sketches and, later, the movie.

"However, the joke is a twist of a much older British phrase that tracks back more than a century to some point in the Edwardian period (1901-1910). There, the line was 'as the actress says to the bishop,' in reference to actresses — whose company could be purchased after performances — confessing their sins to clergymen. It was used the same way as "that's what she said," highlighting an unintended double entendre."