my grandad using my pc

my grandad uses this computer which is in my bedroom to play games on popcap.com but because the computer is in my bedroom he has to use it here
the room is a sate cause of him theres coffee cup all over the place and he empties is pipe into cups and glasses he leaves stuff all over the plae and rearanges my furniture to suit him. he doesnt even live in the same house as me he has his own place with my granny two blocks away its seriously getting on my nerves he tells me its my fault my room is a mess even though it was cleaned four days ago nd i have done about three things to makee it worse and he has done 400 million theres tea stains on everything and black marks from his pipe on more things tht that, even my X360
he acts like its his house when he walks in and demands that i leave and make him tea, im not his f***ing slave he can make his own tea when he barges over uninvited and stops me doing whatever i was doing when he uses my pc he ownloads free trials of games on popcap and being him he downloads it four times berfore he realises that you have to run the installer leaving loads of installers on my desktop messing the whole thing up he downloads football results and then doesnt watch them so i have four or five quite large video files littering the place
worse than all that he puts stuff on my desk my laptop is totally f***ed and a slight bumb could make it crash or whatever and when that happns i gotta spend twenty minuits mending it repositioning it and balancing it out so it will run properly again and he comes downstairs and screams at me "why havent you go that fixed your so useless i was getting my best score ever and your stupid computer broke!" when he knows fair well the problem cannot be solved for less than the stupid thing is worth