ScarJo Inspired Katy Perry Tune

We already know that Katy Perry has a thing for boobs — and that she accidentally exposes her own. But it turns out she's also got the hots for Scarlett Johansson's lips.

Allure magazine recently told the actress that Perry had penned the tune in honour of Johansson. But Johansson said any smooching between her and Perry is never going to happen.

"That's flattering, but my lips are kind of taken," Johansson told Allure. "I had no idea [about the song]. I should get a cut!"

Johansson married actor Ryan Reynolds earlier this year.

Perry's chest has also recently been the subject of rumours. There are apparently those who think the singer's boobs aren't real! We wonder if these fake boob rumours were started by someone who saw them during that recent dress slip...

"How could people think these are fake?" Perry told the U.K.'s The Sun tabloid. "Look at 'em. Ask them! They are as real as real can be.

"One hundred per cent genuine and untouched... well sort of.

"I would never spend money on fake boobs. Shoes, maybe. A handbag, maybe. But plastic tits — no way!"

Despite her adamant denials about having undergone plastic surgery, Perry says she isn't against people who decide to have a bit of work done.

"I am not against people who get things done," she told the tabloid. "A tuck or a lift never hurt anyone.

"In 50 years time, I may look like a Siamese cat in a wind tunnel, but as of this moment, I haven't and the rack is real."

You can see Perry (and her boobs?) when she plays Vancouver's sold out Commodore Ballroom on Jan. 25, Toronto's Kool Haus on March 30 and Montreal's Metropolis on March 31.