The page 123 thing

"So close is Benjamin to Marx's own formulation that the fact these passages are missing from the Passagen-Werk material must come as a surprise."
From The Dialectics of Seeing - Walter Benjamin and the Arcades Project" by Susan Buck-Morss

The page 123 thing is explained :

1. Grab the nearest book.
2. Open the book to page 123.
3. Find the fifth sentence.
4. Post the text of the sentence in your journal along with these instructions.
5. Don’t search around and look for the “coolest” book you can find. Do what’s actually next to you.

Playing School, Irreverently: "whatcha readin'?" meme is the furthest back I could trace the meme path.