Subscribe | UPI Odd Newsletter Subscribe SYDNEY, Oct. 14 (UPI) -- An Australian activist has warned teenage girls in the country to refrain from writing their phone numbers on their backs while sunbathing. Girls, ages 14 and 15, have been spotted sunbathing at Sydney beaches with their phone numbers written on their backs in blue zinc cream in what they described as an attempt to meet boys, the Daily Mail reported Tuesday. Advertisement Concerned adult Nikki Goldstein said it is dangerous for girls to display their "phone number on the Internet or anywhere that could make them a target." "They're in their bikinis, showing off their bodies, objectifying themselves in a way that is, to my mind, a bit trashy," Goldstein said. One of the sunbathing girls, Lizzy, 15, said the plan she hatched with her friends to meet boys has already backfired in a menacing way. "An old guy tried to talk to me. He was trying to take pictures of us," she said.