I agree, it is a strange sensation to suddenly see someone you know from a different context naked.........'strange' in a good way though, lol.
I had similar experience to HiJinx about a year ago. Had some friends of my parents staying with me, I guess they are in their mid 60s. We had all gone to bed and after about an hour or so I realized I didn't start the dishwasher. I put on some underwear just because there were people in the house, as I came around the corner to the kitchen there was the husband standing naked with the freezer door eating ice cream from the carton. Well in the light of the freezer I could clearly see his stuff and the chill of the freezer wasn't giving him any 'shrinkage', lol. He didn't bat an eye and neither did I, he said I caught him having some of the ice cream his wife wouldn't let him have. We made some small talk but what I remember most was the 'smack' sound (in the dead silence at night) his dick made against his leg as he turned quickly from the fridge to the sink to get a drink of water (he had a rather long hanger with a big knob head on it).
The really odd part is that I've stayed at their home and they are quite modest. Getting up in the morning he would have on a big bathrobe and be wearing white briefs (got a peek or two) and a t-shirt under it, leaving me to believe he slept in his underwear. They live in southern California so it wasn't because of the temperature. Maybe he just gets his jollies walking around other people's homes nude, who knows, lol.
I got caught recently by a friends kid (innocent), but it prob goes in a different thread.