SOUTHAMPTON, N.Y. — Phil Mickelson celebrated his birthday Saturday with a burst of temporary insanity during the third round of the U.S. Open.

After sending a bogey putt speeding past the cup on the 13th hole, Mickelson basically snapped. He hustled after the putt – and hit it back toward the hole before it stopped rolling. Apparently the thought of seeing the ball roll off the green was more than the freshly minted 48-year-old was ready to handle, so he gave it a hockey wrist shot back.

Clearly, that violates the rules of the game. Mickelson was assessed a two-stroke penalty for hitting a moving ball, giving him a 10 on the par-4 hole en route to an 81, putting him 17-over par for the tournament.

Why a 2-stroke penalty and not a disqualification?

This is where golf gets into the weeds and the USGA’s ruling is … curious: The USGA determined Mickelson “made a stroke at a moving ball,” but did not purposefully deflect or stop it. Had he done the latter he would have been disqualified.

“Phil didn’t purposefully deflect or stop the ball,” USGA official John Bodenhamer explained, adding that the determination was unanimous.

Mickelson’s answer would suggest otherwise.

What was Phil’s explanation?

He was taking advantage of the rules. He acknowledged the ball would have rolled off the green and rather than try his luck from there, he took the 2-stroke penalty and moved on.

“I don’t mean disrespect by anybody, I know it’s a two-shot penalty, and at that time I just didn’t feel like going back and forth and hitting the same shot over, I took the 2-shot penalty and moved on,” he explained.

“It’s my understanding of the rules. I’ve had multiple times where I’ve wanted to do that, I just finally did.”

However you look at it, it was the kind of thing a 5-year-old does on a bad hole on a miniature golf course. Not exactly what you’d expect from one of the giants of the sport in the U.S. Open. A round that began with fans singing “Happy Birthday” to Mickelson as he walked down the first fairway went off the rails in a very strange way.

It conjured up memories of John Daly hitting a moving ball that rolled off the green during the fourth round of the 1999 U.S. Open at Pinehurst. But Daly was always the combustible outlaw type, whereas Mickelson has a carefully cultivated image as one of the game’s leading ambassadors.

Also inexplicably, Mickelson walked away from the green with playing partner Andrew “Beef” Johnston smiling. Then he kept on with his round and parred the most difficult hole on the course, the 14th, still smiling and acknowledging fans.

A sampling of the Fox Sports commentary that accompanied Phil’s Pholly:

“That is stunning,” said Fox Sports rules analyst David Fay, a former USGA executive director. “The last time I saw something like that was John Daly at the ’99 [U.S.] Open at Pinehurst. That’s basically his way of saying, ‘That’s it, no mas.’ ”

“That was jarring,” analyst Curtis Strange said. “I’ve never seen anything like that from a world-class player in my life.”

“That’s the most out-of-character I’ve ever seen Phil Mickelson,” said analyst Paul Azinger. “He’s putted bad enough that I think he just snapped at how bad his speed was on that putt. He just snapped.”

Prior to that meltdown, Mickelson already was a plus-4 for the day and 10-over for the tournament. He’s never won a U.S. Open, but now he has etched himself a place in tournament lore – for all the wrong reasons.

Yahoo Sports’ writer Jay Busbee contributed to this story.

More from Yahoo Sports:
• Messi’s World Cup misery continues with missed penalty kick
• Brother of NBA forward Zach Randolph killed in shooting
• Suns reportedly exploring trading No. 1 pick for Kawhi Leonard
• Where does Portugal-Spain rank among World Cup’s greatest games?