I'm going to put toilet paper on my roommates desks
What's the purpose of putting toilet paper there?
Because I want to give him a big surprise
What you see as funny may not be as comical to the person you're pranking. If you want to get attention from your roommate, go about doing it in a more positive way so that the relationship doesn't deteriorate.
This is the way I always do things. I wouldn't know what to do if I'm nice like you.
It might be a harmless prank, but you don't know how they are feeling that day. How would your roommate feel if they were very busy and had to deal with additional things at home?