It started on the playground with a first grade classmate. "I saw another kid like hitting her butt so I did it," Castro said.

His Potomac View Elementary School then called the police and wrote him up as a sexual harasser. Woodbridge, MD. school officials described the incident as "Sexual Touching Against Student, Offensive," in their report.

"When I hear 'mommy they called police because I am a bad boy,' that is the message that you're giving to a 6-year-old?" said Randy's mother, Claudia Castro.

Ted Feinberg, assistant director of the National Association of School Psychologists, was stunned by the school's reaction and says 6-year-olds have no idea what those behaviors mean.

The school said that a "misunderstanding" led the principal to call the police, and that "the police never spoke to the child and no disciplinary action was taken by the administration."

According to the state's Department of Education, 166 elementary students were suspended in Maryland last year for sexual harassment, including three preschoolers, 16 kindergartners and 22 first-graders.

In Virginia, 255 elementary students were suspended for offensive sexual touching last year as well.

Two years ago in Texas, a four-year-old was punished for sexual harassment after a teacher's aide accused the pre-schooler of pressing his face into her breasts during a hug.

While a school's priority is to keep kids safe, critics argue the "zero-tolerance" policies can mean zero discretion.

"Overwhelming research suggests that "zero-tolerance" is not effective and often engenders more bad behavior," said Feinberg.

Randy's school has told ABC News that this won't be going on his permanent record, but for Randy's mom, his childhood innocence has been changed forever.

"They are treating him like a teenager or a grown-up … He is not. He is just a child," said Claudia Castro.

Child sex offenders do exist. A Justice Department survey says that kids aged 7-11 were responsible for almost 4 percent of all the sexual assaults committed in the U.S. The question is whether some of the kids being slapped with these sexual harassment labels deserve them.