The puzzle consists of the repeated sentence "Whack me on the side of the head because I have diplopia and it is rough", with each letter doubled, like a person with diplopia (double vision) might see it. Embedded in each copy of the sentence is a single undoubled letter hiding next to a doubled version of the same letter.
Taking each embedded letter in the order presented spells the clue MIND BOMB AND DUSK GROUP MINUS DOUBLE VISION. Mind Bomb and Dusk are albums by the group The The. Taking the "The The" and eliminating the double vision (repetition) gives you the answer, THE.