Phil Mickelson turned 48 on Saturday, an occasion marked by fans singing "Happy Birthday" at every turn.

Unfortunately he ruined it by acting like a 10-year-old at the U.S. Open.

And, much like a 10-year-old, he refused to admit he was wrong.

"If somebody's offended by that I apologize," Mickelson said after running after his golf ball on the 13th green at Shinnecock Hills and hitting it while it was still moving. "But toughen up, this was not meant that way."

Actually it was, because what happened on the slippery 13th green at Shinnecock wasn't just a case of a golfer losing his head momentarily in anger. That, at least, might have been excusable, even for a player in his 27th Open who clearly knows better.

No, this was Mickelson's attempt to be the smartest guy in golf once again. This was his way to bend the rules and take a shot at the USGA at the same time for making the green so difficult.

And Mickelson should know there's no place for that kind of behavior on any golf course, much less in the national championship.

His playing partner surely did.

"It's something you might see at your home course with your mates or something," Andrew Johnston said. "But it was just a moment — I think — it's just a moment of madness."

The moment was one thing. Mickelson's explanation was another.

If the former wasn't enough to get him kicked out of the Open, the latter should make everyone in golf take pause.

Think about it. One of the greatest players in the world literally running after a putt moving down a hill and swinging his putter like a miniature hockey stick to knock it back toward the hole.

Then explaining it all away by saying he was simply taking advantage of the rules.

"I know the rules," Mickelson said. "It's a two-shot penalty. I gladly take the two-shot penalty."

Mickelson got his penalty, though it hardly mattered. He shot 81 in the third round and at 17 over par wasn't going to be a factor on Sunday anyway.

But for arguably the greatest short game player in the world to insist he did what he did to avoid playing another shot from in front of the green was disingenuous at best, and dishonest at its worst.

He could have easily made a score better than the 10 he ended up writing down on his scorecard. But he simply wasn't going to try.

Worse yet, there was clearly some premeditation involved. Mickelson said he had thought about doing the same thing many times, including on the tricky 15th green at the Masters.

And he proudly pointed out that he took 11 drops at a tournament in 2006 before getting one he liked and went on to win the tournament.

"Sometimes it gets a little goofy, sure, but it's all within the rules," he said.

Players bending the rules is nothing new, of course. But imagine what would have happened if Mickelson would have tried the same stunt at Augusta National, which doesn't tend to tolerate such behavior.

The guys in the green jackets would have sent him packing before he had a chance to change out of his golf shoes.

Yes, Saturday was brutal at Shinnecock, where the wind blew and the final twosome of Dustin Johnson and Scott Piercy combined for an 81 on the front side. But Tony Finau teed off 33 minutes before Mickelson and managed to shoot a 4-under 66, so it wasn't like it was totally unplayable.

Mickelson has made no secret in the past of his dislike for some Open setups, which might be one reason he's never won an Open. Yet he came this week talking about how it should be a great tournament because it was set up for skill to win, not luck.

Then he goes out and makes a "Happy Gilmore" move on one of golf's biggest stages.

John Daly did it in the 1999 U.S. Open at Pinehurst, so it's not like it's never happened before. But Daly never made any pretense about who he was, unlike arguably the most popular player in the game.

Johnston and Mickelson shared a laugh about it going off the 13th green, but Johnston wasn't quite sure what he was laughing about.

"It was so strange because I don't think anyone had them thoughts," Johnston said. "No one ever has them thoughts. And it just happened. And that's all I can really say about it."

Mickelson could say more, plenty more.

Starting with a real apology for a dumb idea.