Very awkward this one. It was maybe twenty years ago. I used to sleep naked all the time in summer. My parents-in-law were staying with us but I got up very early to get ready for work so I just went straight to the bathroom. I was sitting having a crap! completely naked when my 60+ mother-in-law walked in. She kind of stalled for a moment, made the slightest gasp noise and quickly backed out and shut the door I thought she must have felt as embarrassed as me but one second later she opened the door again, stuck her head and shoulders in to wish me Good Morning and gave little smile and nervous laugh. I think she was trying to take some tension out of the situation but the second intrusion annoyed me and she noticed that and left again.