Long story short. I get home from a night out and one of my housemates has put one of her friends in my bed for the night, not knowing if I was coming home or not. 
I get home, get into bed, we chat for a bit then go to sleep.
Wake up the next morning to both my other housemates telling me they are going to tell my girlfriend, because they suspect we must have had sex, even though nothing happened.. AITA? 