[pen] Have you noticed how coffee expands when freed from the constaints of a cup/mug? One knocked over mug of coffee can flood an entire desk, soak into reams of paperwork and fill a couple of drawers.
And remember that if you do spill coffee on your desk: save the phone and the papers before worrying about the keyboard (keyboard £20, phone £200 if it's a clever one, papers probably several hours of your time).