After university I moved in with my girlfriend's mother (and her sister and brother though my GF didn't live there) for a couple of weeks while I found somewhere to live. I stayed for five years.
During that time we moved house and a new room had to be built to accommodate me, me and the girlfriend split up, her sister and then her brother moved out and her mother found a new boyfriend. It was seeing him naked in the hall one night that finally made me realise it was time to leave.
that shit is fucked up