I think it's called "1-2-3"
Here's how it works:
Grab the nearest book (really, the one closest to you at the moment. Don't go looking for a 'cool' one)
Turn to page 123.
Find the 5th sentence.
Post it here in the comments tail.
Amazing what some sentences look like out of context...
Down then fell the hall and Gawain fell as well,
Falling in the ground where both his arms were broken,
So with my left hand I clutched my beloved sword
And struck off Modred's head and it went rolling over the ground,
And I sliced the queen into pieces with my beloved sword,
And after that I dropped her into a dingy pit.
Of course, the closest book to me was The Norton Anthology of English Literature because I was making out my class's final exam. This is from Layamon's Brut (ca. 1190). No wonder I don't teach this story in my class...ick.
Surely you can come up with something better...