Act a bit lor. Take out some of the more important hardwares of
your computer. Then when they come, on the computer and then act
shocked a bit, say got problem lor. Try to 'fix' the computer
throughout their visit to your house, and try to lock your room
while you're 'fixing' your computer.
Or say you got project need to rush so need to use the computer.
Your parents should not be unreasonable to scold you or
something.
To be honest, I don't see the reason why your cousins must use your
computer when they go your house leh. It's not a necessity, just a
privilege. Tell you parents that you don't like your cousins to be
using your things lor. Say you need some privacy. See how they say
lor.
