Snow Crash, by Neal Stephenson

Edit: oh heck. It might have been The Diamond Age.

Edit 2: search yielded

“Bud knew a guy like that who’d somehow gotten infected with a meme that ran advertisements for roach motels, in Hindi, superimposed on the bottom right-hand corner of his visual field, twenty-four hours a day, until the guy whacked himself.” --Neal Stephenson, The Diamond Age