A less-than-well-known joke about Fereydoon's stalker (the household maid) from the game Wild ARMs 5. The "household maid" is a creepy woman who watched (or "witnessed", as she says) Fereydoon and Lucille spending some "quality time" with each other, and tells the person playing the game all about it. It's an easter egg, so very few people who have played the game actually know about it.
Outside of the WA5 cult, this phrase can be used to cause awkward silences.
Original Phrase: I witnessed it all... Fereydoon the Sentinel and a maid from Lady Diana's mansion, having tea and getting VERY cozy with each other...
Example of use in real life:
Mom: What were you doing up there with your girlfriend?
Your older brother: Uh...watching a movie?
Your younger sister, who was in the other room and heard it all: The household maid witnessed it all.