Someone keep this cat off my desk and lap somehow. Actually just desk. Lap is ok.
Anyway, it's really not... HEY, STOP CHEWING ON THAT!
As I was saying, just keep a laser pointer on your desk. When the cat gets on the desk, shine it on the wall where the cat can see. Wiggle it a bit. Get the cat to chase it, and use it to lure the cat off the desk back onto the floor.