Police filed the complaint Sunday after reading a newspaper article about the young rapper's music videos, The (Brockton) Enterprise reported.
In the videos, Luie Rivera Jr., aka Lil Poopy, a Brockton fourth-grader, is seen in various sexually charged situations, slapping women's bottoms or the women dancing inappropriately with him, police said. In one video, Luie is in a simulated sex situation with a female on a dance floor. People watching throw dollar bills at the child.
"It's a bit much for a 9-year-old. It warrants the attention of the Department of Children and Families," police Lt. David Dickinson said Sunday.
The complaint was filed with the state Department of Children and Families, which can choose to investigate the alleged abuse or neglect.
The boy's father, Luis Rivera, said that his son "is not doing anything wrong" in the videos posted to YouTube.
"I'll call my lawyer first thing in the morning," Rivera, 30, said when informed of the police complaint against him Sunday afternoon. "He's not doing anything wrong. He's acting."
Local activists say they agree with the police.
"It's disgusting," said Brockton community activist Ollie Jay Spears, the founder of the Brockton Peace Crusaders, a group aiming to steer at-risk youths in the city's roughest neighborhoods away from guns and other violence.
"With the girl bent over and the other girl grinding into him," Spears said. "A 9-year-old with stacks of money and rapping about glorifying the drug trade, and demeaning women? A kid at the third- or fourth-grade level, talking about coke? It's not entertaining. That's borderline child abuse."