Whoever is the last one who can't find somewhere in the sink to put the dish, does the dishes.
Your underwear, is your underwear. Mine is mine, I'll wash it myself.
Whoever is the last one who can't put something in the trash because it's full, takes out the trash.
If you're the one who uses the bathroom alone, clean it whenever. If it's shared, it's whoever gets grossed out the most. It gets messy.
There is no vacuum. At some point, it gets broken. No one is going to buy a new one.
If you don't cook it yourself, you starve.
And that's how it goes with a male room mate. I can't wait to get out with the SO.