O'Connor, the second youngest of seven boys - four of whom graduated from Judge - couldn't dare take sides against the family.
"That's really the main reason I wanted to come [to Judge]. I just wanted to keep the tradition going," he said.
The 18-year-old Mayfair resident's seven points and eight rebounds helped the Crusaders (7-11, 4-5 Catholic League) spoil Senior Day for the Raiders (10-8, 2-7).
Sophomore guard Quincy Reed led Judge with 15 points on just 4-of-8 shooting (3-for-6 from three, 4-for-4 at the line). Junior guard Will Brazukas and freshman wing Marc Rodriguez each added 12.
"We haven't beaten Ryan since my freshman year, so this feels really, really, really good," O'Connor said. "We got spanked 2 years ago. Last year, we had a tough loss [65-61, at Judge] that we should have won."
The ambience in that one: "One of the greatest atmospheres I've ever witnessed at any level of basketball," O'Connor said. "It was insane."
Yesterday had its raucous moments. However, most notable was when Ryan senior heartthrob Brendan Horan (18 points) scored, which elicited shrieks - and more than one "we love you, Brendan" - from adoring female fans.
With all four sets of bleachers open for business, plenty packed the gym, but the action on the court wasn't conducive to much clamor.
Judge led, 8-5, after the first frame, and 19-17 at halftime. In fact, late in the first, a Ryan fan prodded the Raiders' student section with, "You have to be louder than that!"
Noise, what noise? Remember, O'Connor grew up in a house with seven boys.
"[The house was] very loud," he said. "There were always a ton of fights. Pushing, shoving, and wrestling over basketball and football and video games. It was never calm."
As he spoke, several chuckling teammates filed out of the locker room with catcalls of "Yeah, J-Butter. Yeah, J-Butter!"
Perhaps respect from his mates abounds because O'Connor, ahem, "J-Butter," has overcome several injuries to emerge as a senior starter.
A broken left wrist wrecked half of last season, while torn ligaments in his left foot and ankle in eighth grade hindered some of freshman ball.
Toughness, perseverance and work ethic - traits instilled by Mom and Dad - saw him through.
Since Jon Michael's father, Gerard, passed from cancer a decade ago, his mother, Theresa, has steadied the family.
"Yes, my mother is a tough woman," he said. "She works 6 days a week. She's always doing everything for us. She's just always been there taking care of us forever, pretty much."
Twins Matt and Mark, Shane (played baseball at Lincoln), Jimmy, Danny and Liam are his siblings. O'Connor said memories of Dad are fuzzy, but he remembers Gerard as a good athlete at 6-4, who had skills on the court despite faulty knees.
Sports have been foremost in his life, so O'Connor hopes for a career as a sports writer. His 3.3 GPA could help. He also reports hoops interest from Valley Forge Military College.
"That's really my goal," O'Connor said, "to play college basketball wherever, whenever, for whomever; as long as it's a good school, I can get an education and have fun playing."
On Twitter: @AceCarterDN