Think you know someone? Wait until you live with them and watch them shed their “appropriate behaviour for human interaction” skin as soon as the removal van has left. Nothing is out of bounds when you are shoved into a confined space with someone for an extended period of time.
It is as if they reveal themselves, elegantly emerging from their cocoon, in a moment I could only describe as the mask-removing scene of the original Predator movie (complete with sinister laugh).
This just brings up a point of how well you know these people prior to moving in with them. It is a big test on cohabiting and sees a lot of friendships and relationships disintegrate. By the end of it, you can have a completely different perspective on that person.