LOS ANGELES » When Mayor Eric Garcetti declared it "a big f—ing day" for LA, he brought 19,000 hockey fans to their feet, lit up the Twitterverse in delight and, oh yeah, left some folks scratching their heads, wondering just what the f— the normally soft-spoken elected official was thinking.

Having shed his pinstriped suit of choice for a hockey jersey Monday, Garcetti stepped in front of the TV cameras and a full house at Staples Center, where the Los Angeles Kings had won hockey’s Stanley Cup championship just three days before.

"There are two rules in politics," Garcetti told those celebrating the victory. "They say never ever be pictured with a drink in your hand. And never ever swear.

Then he added dramatically: "But this is a big f—ing day. Way to go, guys."

Within minutes, Garcetti’s remarks were trending on Twitter and appearing uncensored on YouTube, just as Fox Sports West was apologizing for letting them get on the air.

"He said that?" Thomas Hollihan, an expert on political discourse, civil society and contemporary rhetorical criticism at the University of Southern California, asked incredulously.

This was, after all, not some drunken musician accepting an award somewhere. Nor was it a celebrity caught up in a silly dispute captured by the cameras for TMZ. This was the mayor of the nation’s second-largest city, gleefully shouting it to the masses.

"When you’re an elected official, people have a higher expectation for your speech, your conduct and context than they would if you’re an entertainer," said Hollihan.

He added he hoped Garcetti, whose public persona is normally about as mild as his city’s weather, wasn’t trying to boost his hipness cred.

Although the F-word’s shock value is declining, Hollihan said, it’s never smart for a politician to toss it around in public, even in front of a crowd of screaming hockey fans.

"The little old ladies in the valley are going to hear this too," he said, referring to the city’s more conservative San Fernando Valley, where Garcetti grew up before moving to the hipper Silver Lake area. "As are the church people in neighborhoods where they are not hockey fans, but they care a lot about conduct and character."

But where putting the word out over the airwaves once would have prompted a federal investigation, that’s not so much the case anymore.

When David Ortiz of the Boston Red Sox let it slip last year during a televised event honoring first-responders to the Boston Marathon bombings, the chairman of the Federal Communications Commission himself Tweeted that it was no big deal.

"David Ortiz spoke from the heart at today’s Red Sox game. I stand with Big Papi and the people of Boston," said Julius Genachowski

And when, thanks to a bank of TV microphones, the world heard Vice President Joe Biden’s whisper to President Barack Obama, "This is a big f—ing deal," as Obama was about to sign the Affordable Health Care Act, the slip was quickly forgotten.

Of course Biden didn’t mean for anyone but Obama to hear him. And Ortiz said afterward he got caught up in the moment and never meant to say what he said.

But the mayor’s official Twitter account did repeat much of what he said — with the hashtag BFD.

Appearing on "Jimmy Kimmel Live" later Monday, Garcetti got a loud round of cheers when Kimmel told him "I enjoyed your performance at the rally today."

Garcetti replied, "I got a little ahead of myself. But you’ve got to remember, we didn’t win at lawn bowling, we won in hockey."

The mayor added, "Kids out there do not say what your mayor said today."