Cee Lo Green performs in Times Square on Dec. 31, 2011. (Michael Loccisano/GETTY IMAGES FOR NIVEA)

Instead of singing, “Nothing to kill or die for. And no religion too,” Green sang, “And all religion’s true.” Not surprisingly, changing the words to — and part of the message of — the iconic song did not sit well with Lennon’s fans, who took to Twitter and the comments sections of various Web sites to voice their displeasure.

The “Forget You” crooner and “Voice” judge apologized, tweeting, “Yo I meant no disrespect by changing the lyric guys! I was trying to say a world were u could believe what u wanted that's all.” He later deleted that tweet, replacing it with, “Now playing: we just disagree: dave mason.” (Sample lyrics: “There ain’t no good guy, there ain’t no bad guy/There’s only you and me and we just disagree.”)

Cee Lo should not have been shocked by the response. Lennon’s fans are fiercely and famously protective, a fact that has been proved on numerous occasions. Here are just a few celebrities and organizations who haven’t had to “imagine” what it’s like to tick off the John Lennon faithful.

Lady Gaga plays Lennon’s white piano

In summer 2010, Lennon’s son Sean tweeted a photo of Lady Gaga playing his father’s white grand piano — the one that appears in the video for “Imagine.”

That image was not a welcome sight to some Lennon fans, including one who tweeted (via Entertainment Weekly), “WHY WOULD YOU LET LADY GAGA PLAY ON JOHN’S PIANO?”

”Pianos are meant to be played,” Sean Lennon tweeted back in Gaga’s defense. “Why is everyone so uptight? What should we do, lock it away in a dusty room? So judgmental.”

John Lennon appears in a car commercial

Footage from a 1968 interview with Lennon was used in an “anti retro”-themed commercial for the Citroën DS-3 in 2010.

“Looking backwards for inspiration, copying the past — how is that rock ’n’ roll? Do something of your own. Start something new,” Lennon says before images of the car flash on screen.

MusicRadar.com reported at the time that Lennon’s widow, Yoko Ono, approved the video’s use. This prompted an angry reaction from fans who didn’t appreciate Lennon’s words being used to shill cars. Again, Sean Lennon acted as his parents’ defender.

“Look, TV ad was not for money. It’s just hard to find new ways to keep dad in the new world. Not many things as effective as TV,” Sean Lennon tweeted (via NME). He later sympathized with angry fans while still defending his mother’s good intentions: “Having just seen ad I realize why people are mad. But intention was not financial, was simply wanting to keep him out there in the world.”

The ad’s YouTube video is still up and garnering comments, including the very apt, “WHY WHY WHYYYYYYYYY.”

Lennon appears from beyond the grave in PSA

Perhaps nothing was as creepy (albeit well intentioned) as the 2008 PSA from One Laptop Per Child. The spot for the charity showed the late singer delivering a plea on behalf of the charity by stating, “Imagine every child, no matter where in the world they were, could access a universe of knowledge” — despite the fact that he had been dead for nearly three decades. (The ad was voiced by an impressionist.)

Lennon fans and non-fans could probably agree that this was not the best idea. As Boing Boing wrote, “Digitally, it’s creepy, and reeks of defilement no matter how well done.” The video still lives on YouTube, where the comments have been disabled.

“Real Love” used in JC Penney commercial

In 2007, Ono gave department store JC Penney the rights to use a home recording of Lennon’s “Real Love” in a commercial that featured an adorable, bespectacled little girl. According to a press release from the company, it was only the second time Ono had licensed a recording of Lennon singing — not just one of his songs being re-created.

The resulting ad is very sweet, but this didn’t stop fans from criticizing Ono for licensing the song. Fox411’s Roger Friedman noted that it wasn’t the first time Ono, who he described as “much-disliked,” had sold merchandise under her late husband’s name, adding, “But using a rare, acoustic home recording — and a beautiful, haunting one at that — as the Christmas song for a department store seems particularly greedy.”

Pete Nash, the chairman of the British Beatles fan club, told the Guardian, “Obviously you can’t ask Lennon himself if you can use his song, but if you could, I'm 100 percent sure his answer would be to tell JC Penney to [expletive] off.”