"There are cubicles. He could have used a towel as well."
But commenters weren't convinced.
"You were sat in a changing room and you are shocked at someone getting changed? I'm confused?" one wrote.
"So you were upset because you saw a man's penis in a male changing room? Are you female? If so you shouldn't have been in there," said another.
But a few agreed with the mother, saying adults shouldn't get naked in front of other people's children.
"No, if you might be seen by other children (or in my apparently very repressed family, even your own), you don't just let everything hang out."
"Not prudish and I know we've all got a body, but this was totally unnecessary."
But a lot of people wondered why naked bodies in a changing room were even an issue, saying that children weren't "squeamish" about nudity.
"Rather than encourage children to be scared and ashamed of our bodies why not accept them for what they are?" one wrote.
"Children are not scarred by bodies. Children are not at risk in the men's because they are accompanied by a responsible adult."