As Phil Murphy uttered the final phrase of his official swearing-in as New Jersey's governor Tuesday, his 20-year-old son flashed a sign with his right hand and made a quick glance into the audience.

The signal, which resembled an upside-down OK sign, by Josh Murphy is frequently associated with the so-called circle game, which was featured on the television show "Malcolm in the Middle." In the game, being tricked into looking at the circle results in a punch in the arm.

A Murphy spokesman, Dan Bryan, confirmed later in the day the governor's oldest son played "the circle game" just after his father was sworn in.

Josh Murphy is a student at Tufts University in Boston.

The signal was first pointed out by conservative website savejersey.com, which mentioned a different OK hand gesture has sometimes been used by white supremacists.

The Anti-Defamation League states on its website that the other gesture is a hoax that originated in February 2017 on the website 4chan. An anonymous user announced, "Operation O-KKK," telling other members to flood social media and claim the "OK" sign is a symbol of white supremacy.

"The 'OK' (hoaxers) have tried to take innocuous items, symbols or gestures and falsely attribute white supremacist meanings to them in order to fool liberals and get them to spread such false messages," the league claims.

Anthony G. Attrino may be reached at tattrino@njadvancemedia.com. Follow him on Twitter @TonyAttrino. Find NJ.com on Facebook.