6) Leaving doors unlocked / drawers or cabinets open, etc.
Petty, I know, but you and I both know that this is something to fight over especially if you have to tell them every single time not to leave the doors unlocked or the cabinets open.
5) Fight about your differing study habits
This is especially true if one of you prefers nice and quiet while the other cannot focus without music playing in the background.
4) When you / they keep forgetting to turn any appliance off
Do I need to spell this out? I mean, not only is it a risk for causing a fire (like what my momma always tells me) it’s also a waste of electricity! The bills, man, bills.