Steve Jobs thinks you're fat. Or at least your fingers are.

Jobs dialed in to Apple's earnings call this afternoon and took on, among other topics, the usability of a 7-inch touch-screen tablet. Though many of Apple's competitors are introducing or plan to introduce tablets in that size, it's not ideal for a touch-screen device, he told investors.

"It's meaningless unless your tablet also includes sandpaper, so that the user can sand down their fingers to around one quarter of their present size," he said.

Normal-size human fingers are too big to be able to accurately hit icons on a screen that size, he claimed.

"Apple has done extensive user testing and we really understand this stuff," he said. "There are clear limits on how close you can place things on a touchscreen, which is why we think 10 inch is the minimum screen size to create great tablet apps."

But it's not just our pesky fingers that are the problem. He also trashed the screen size and resolution of 7-inchers.

"One naturally thinks that a 7-inch screen would offer 70 percent of the benefits of a 10-inch screen...this is far from the truth. Seven-inch screens are 45 percent as large as an iPad," Jobs said. "This size isn't sufficient for making great tablet apps."