Women walking at Christchurch's Spencer Park Beach are concerned about naked men hanging around the area, prompting warnings on social media and a complaint to the police. A woman who was at the beach on Friday said she was thinking about taking a last swim before winter when she noticed a man in her peripheral vision about 10m away. “It’s a fully naked, white male, probably in his 40s-50s. I took one brief look at him and initially just thought he was skinny dipping and thought ‘weird but ok’,” she posted on Facebook. “Then I looked again and realised he was grinning at me and touching himself right next to me.” She was stunned and didn't know what to do or think. “He kept touching himself while looking at me, and I anxiously just stared at my phone for a few seconds trying not to look at him, then walked quickly toward the dunes. “When I looked back he was gone.” They were the only people on the beach at the time, the woman said. She reported the incident to police and went online to warn others.…