It's right there in the URL: "the_cup_holder_joke" Besides, the top of the computer case, usually mere inches away from the CD tray, is a whole lot more stable

It's right there in the URL: "the_cup_holder_joke" Besides, the top of the computer case, usually mere inches away from the CD tray, is a whole lot more stable, and doesn't run the risk of knocking the drink over when software closes the tray unexpectedly. The only people who ever used the tray as a cup holder, did it for the obvious meme. Note that "holder" makes it obviously a joke since the hole isn't even big enough unless it's like a shot glass. And they were much to soft and flimsy to use as a mini table.