If you don't want to know the circumstances surrounding Sunday's entry in this slideshow, then don't read any further...
[spoiler]Sunday's quote:
Ep #679 (1969) - David - 'Well then I MUST have been talking to myself, right?'
From "Robservations 10/7/02 - #678/679 - Maggie Follows David Into Quentin's Lair"
Liz enters the room and asks who he's talking to, but Quentin is gone. David claims he was talking to himself. Liz asks if it's about the game he and Amy play. David doesn't know which game, but Liz says it's the one of the phone. David lies about a giant named Lars who lives in a house by the sea--Lars is being held captive by a wicked old witch. Liz is annoyed, feeling David is too old for games involving giants and imaginary people
[/spoiler]
Obviously the Robservations references the quote, but not directly as such...
And this is the second quote from this ep. The first (David - 'You MUSTN'T TELL!') was back on June 7th of 2020.