This prank sure is ‘awksome’ and makes your buddy go crazy as most of the times no one thinks of keyboard layout being changed, and its a fact that there are far less people who know that you can actually change the keyboard layout for good. Funnily enough, they think that the PC has gone nuts.
To make this prank happen, All you have to do is to change the keyboard layout. You can simply access those layout settings under language option in windows control panel. For example you change the keyboard layout to Dvorak(scientifically, this layout is much more efficient then the regular QWERTY layout.).