Robert Goodwin, 41, was engaged in a heated disagreement with the principal of his son’s elementary school last week over a picture his son drew in art class.

His 10-year-old’s drawing of “Gru” from the children’s movie “Despicable Me” depicted the character “shooting ping-pong balls at his minions,” Goodwin told the Boston Herald. School officials reportedly deemed the drawing as sexual in nature.

So the Arlington, Massachusetts, dad apparently thought an additional visual aid would help.

Image source: WBZ-TV

Image source: WBZ-TV

According to WBZ-TV, the school said Goodwin became agitated, removed his gun license from his wallet, and showed it to Stratton Elementary School principal Michael Hanna.

“During that discussion I compared my legally owned license to carry firearms with the picture that my son drew,” Goodwin told WBZ.

Goodwin also indicated he had access to firearms at home, Arlington police Chief Frederick Ryan told the Herald — all of which reportedly left the principal feeling threatened, a charge the father denies.

“I did not threaten [Hanna’s] life in any way,” Goodwin told the Herald regarding the Wednesday incident.

Police ordered Goodwin to stay away from the campus for the rest of the school year, save for dropping off and picking up his son, the Herald reported. According to WBZ, police also showed up at Goodwin’s residence, revoked his firearms license and removed his hunting rifle — though he hasn’t been charged with any crime.

After the incident, Arlington Public Schools Superintendent Kathleen Bodie sent a letter to parents that read: “This argument certainly went above and beyond the scope of a normal disagreement, and therefore the policies and procedures that Arlington Public Schools have in place were immediately activated to make sure that students, faculty, and staff remained safe.”

Image source: WBZ-TV

Image source: WBZ-TV

Goodwin said the school is treating him unfairly and that he’s no threat or danger to anyone.

“I’m sad because I think we have to transfer out of the school,” Goodwin told WBZ, noting he feels badly for his 10-year-old boy. “He’s going to be bummed he doesn’t get to hang out with all of his friends.”

WBZ noted that Goodwin, who said he’s a rapper, can be seen in at least one rap video on YouTube wielding knives.

UPDATE, 1 p.m.: TheBlaze on Monday contacted Superintendent Bodie’s office and was told she’s scheduled to address concerns from parents at Stratton Elementary School starting at 1:30 p.m. Monday. In addition her office noted that Bodie will issue a statement at 5 p.m Monday on the matter.

A call to Principal Hanna wasn’t immediately returned Monday, but according to Bodie’s letter to parents, Hanna is joining her Monday to answer parents’ questions.

TheBlaze attempted to contact Goodwin on Monday and will update this story after speaking with him.

WCVB-TV in Boston reports that police seized the firearm from Goodwin’s apartment on Friday morning and that Goodwin had his son removed from school on Friday as well. The station added that police were standing guard at the school Friday.

Goodwin’s YouTube rap videos appear to fall under the moniker ContextFlexed, also apparently the name of his blog, in which he goes by “Flipside.” Here’s his blog bio: “Flipside is a rap musician and political activist from Boston, MA, former publisher of Haters’ Magazine and opinionist under the name Schlomotion, Maturin20, Contextflexed, and Flipside.”

In Goodwin’s most recent blog entry, he calls conservative activist Pam Geller a “c**t” and savagely criticizes conservative authors David Horowitz and Robert Spencer.

Goodwin’s YouTube bio under his “writings” note a book he’s written called “Why I’m Better.” The book description:

Boston rap emcee and political activist Flipside gives a discourse on current events, revolution, social outlook, music, and generally how to be better at everything. The book is an example of thought as weapon and word as action.

Goodwin has uploaded numerous rap videos on his YouTube page, but the one clip noted in multiple media reports, “2foxalypse Now,” depicts him holding and swinging a pair of knives. (Content warning: Rough language ahead):

WCVB reported that no knives were seized from Goodwin’s residence, citing police.