Books
You're one hundred percent positive that the ship which is crashed on the bottom of this ocean is the ship which you said you were one hundred percent positive could one hundred percent positively never crash?
— Douglas Adams · Young Zaphod Plays It Safe
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker is incredulous and piles on repeated certainty to expose a contradiction: the ship that was guaranteed never to crash is now wrecked on the seabed. Stacking 'one hundred percent' again and again makes the earlier boast sound hilariously foolish.
Context reviewed