Relationship Stress-Tests:
Editing each other's work.
You know what? you're derivative. How does that feel? Doesn't feel good, does it?
Playing Portal 2 co-op mode
Put your portal there.
where?
there.
where?
There for fucks sake, there.
Where?
Assembling IKEA furniture:
Oh No! We were supposed to be using the medium-small screws, not the medium big screws!