My girlfriend lives in London now but is from Manchester. While having sex, we could hear two guys out on the street talking about their flat and rent (her room is about half a level above the street, so no one could see in the windows). At some point one of the guys in the convo said 'I've only been to London twice and that was both the best times of my life, I met a chick from Manchester that lives in that window right there." My girlfriend, while on top of me stopped and went bright red. That's how I found out she had been cheating on me.