My stepfather used to walk around the house in the evening and morning with just a towel round his waist. You could clearly see the outline of something dangling there.
At the time my sister and I were teens and he also did it when I used to stay as an adult. He'd been in our lives since the ages of 8 and 11.
I'm not talking about just walking from bedroom to bathroom but round the house, in the kitchen making tea, coming into our bedroom etc.
It always made me very uncomfortable and having a DH who won't even walk around in boxers when DD is around, I think it was rather odd?