ABC News' Cecilia Vega reports:

Among the hottest activities on social media these days is Instagram's beauty contests, where young girls go head-to-head in cyber beauty pageants online and on their phones, allowing anyone, even complete strangers, to vote for who is the "prettiest."

There are no crowns in this beauty contest, other than the winner's getting to call herself the prettiest of the bunch. The losers, however, get a big, red "X" slapped on their photos.

The girls are so young that ABC News is not showing their faces, but the cyber pageant with a "Mean Girl" twist is all the rage.

Asked whether they had come across the competitions, every student in a group of students at a Massachusetts high school indicated that they had.

"It was almost entirely almost all girls, and the ones who had the most 'likes' was girls wearing the most skimpy outfits," one teen said.

Among the many questions is why a girl would subject herself to this kind of judgment.

"Every girl wants to know what other people think of her," Rachel Simmons, author of "Odd Girl Out," said. "There is no app, no software that will take away the anxiety. That is part of growing up."

Instagram issued a statement saying that parents should monitor their kids online and that the online photo-sharing service takes precautionary measures against inappropriate behavior.

"We are aware this is a trend taking place on virtually every media platform that teens engage with. We work hard to make Instagram a safe, interesting and vibrant place for teens to spend time and express their creativity through photos," the statement read. "As with other social products, we encourage parents to take an active role in understanding what their kids are posting and who they are sharing with."

But seeing children so potentially vulnerable online worries parents like Hollee Actman Becker, and writer and social media consultant. Her 10-year-old daughter inadvertently ended up in an Instagram cyber beauty pageant after someone posted her photo there.

"It hits you in the gut," Becker said. "Like 'Oh my God, why is this happening and why is my child involved in this?' … I think it's so important to get in there and teach them the importance of supporting each other and celebrating who they are on the inside, not what they look like on the outside.