Click photo to enlarge
Cee Lo Green, left, and Gwyneth Paltrow perform at the 53rd annual Grammy Awards on Sunday, Feb. 13, 2011, in Los Angeles. (AP Photo/Matt Sayles)

The first time many of us heard Cee Lo Green's fantastically catchy, obscenity-heavy "(Expletive) You," was like seeing a bolt of lightning strike just a couple of blocks away. It was a bit shocking and kind of fun in a dangerous way. We cleared our heads and waited for the groundshaking roar of outraged parental thunder that usually accompanies such pop music naughty talk.

Nothing.

No torches, no Capitol Hill subcommittees, no boycotts.

Same goes for some other recent mainstream hits, like Rihanna's "S&M," Lil Wayne's not-so-subtle "Lollipop," and Britney Spears' new single "Hold It Against Me," (which, to be fair, isn't nearly as inflammatory as when she was a 17-year-old asking to be "hit" again in "Baby One More Time").

Where's the outrage? Mainstream culture seems to be taking dirty lyrics in stride. Perhaps because there's more competition for shock value these days on cable TV (MTV's teen-sex drama "Skins" has drawn rampant criticism) and on the Internet. Or maybe people have other things to worry about, like the economy and gas prices. Or, as some suggest, maybe they've just grown used to it.

"For the most part, the more things change, the more they remain the same," says John Covach, a rock historian and chairman of the music department at University of Rochester. "Was Britney Spears any more provocative than Elvis was in 1957? Is Lady Gaga today even as shocking as Madonna was in the 1980s? If we are less sensitive to sex and vulgarity in music today, it could be because most parents, and even grandparents, have seen all this before."

In Cee Lo's case, his catchy pop hit last year basically cut through the double-talk of decades of spurned-lover songs by barking out the most dreaded two-word insult in the English language. It was bold. To some, it was even admirable. Others may have thought it bad form.

But it worked. The initial Internet buzz was huge. Then, as many artists have done since the mid-1980s outcry over explicit lyrics, Cee Lo offered a clean version of the song, replacing one F word with another F word to become the much more marketable "Forget You."

Not that anyone was fooled. Especially at the Grammys nearly two weeks ago, when Cee Lo performed the song with Gwyneth Paltrow and "... the Muppets. That's right -- the furry little things that teach children how to count to five in Spanish. Not only was everyone singing the clean version, they were singing "Sh" instead of the obvious, potty-centric four-letter word in the original version. Though a smiling Paltrow didn't alter anything when singing to Cee Lo "I hate your ass," in front of all those innocent Muppets.

Afterward, any outrage over the song only concerned how Cee Lo didn't win a Grammy for song or record of the year.

"We hear it everywhere," says Sue Thompson, a Delaware-based image advisor and etiquette trainer. "We don't care anymore, and when we do, we're considered aberrant."

Cee Lo happens to be touring this year with Rihanna, who has a big hit with "S&M," during which she sings plainly about various, nonenhanced, interrogation-technique uses of whips and chains. Lil Wayne scored a major hit with the sexed-up "Lollipop" as well, among other recent examples.

This isn't death metal or hardcore hip-hop. This is mainstream music largely aimed at teens and their disposable incomes. And to some, the lack of public reaction is outrageous.

"When Rihanna, a victim of assault (by then boyfriend singer Chris Brown), eroticizes violence, she is perpetuating the cultural myth that women want or deserve to be abused," says Brooke Axtell, an advocate for survivors and domestic violence and sexual assault. "In the wake of international coverage on her brutal beating by Chris Brown, singing a song like 'S&M' only normalizes dating violence."

Covach, at the University of Rochester, points out that suggestive lyrics go back to at least the 1920s' African-American music, only it was presented in playful metaphors, and extended through the '50s and early '60s ("Rock Around the Clock" was not exactly about dancing all night). Ed Sullivan famously made the Rolling Stones change the chorus of "Let's Spend the Night Together," to "Let's Spend Some Time Together," and the FBI actually spent two years investigating the lyrics to the Kingsmen's version of "Louie Louie." (No charges were brought; the words were dismissed as "unintelligible at any speed.")

The tide began to shift some in the '80s, Covach says, when Led Zeppelin's Robert Plant groaned his way through "Whole Lotta Love," and punk bands began completely disregarding the rules governing vulgarity. By the time hip-hop followed punk's lead in the '80s, Tipper Gore and the PMRC (Parents Music Resource Center) were pushing back, leading the charge to put warning labels on records with what some deemed inappropriate content for youngsters.

That was about the same time television got involved, and artists could both show and tell what they meant on MTV. Which may have helped desensitize people even more to controversial lyrics.

But if society has indeed developed a thicker skin with regard to dirty lyrics, not everyone is happy about it.

"Yes, we are inured to the foul language in music," says Thompson, the etiquette trainer. "It's not because we now have some thoughtful revelation that (raunchy lyrics) don't send kids to hell. It's because, as a society, we have grown raunchier and less self-controlled, and lyrics, as well as our behavior, our clothing, our entertainment, and more, are sinking to new levels of debasement."