Sideshow: A Rihanna sex tape? No, no, no ...

Rihanna

and

J. Cole

did

not

make a home sex vid, the Barbadian beauty tweeted on Thursday, denying various rumors, including a RadarOnline report that Hustler honchos have seen the tape, which is up for sale.

"We don't believe U, U need more people...AND ofcourse an actual sextape!" Rihanna tweets. J. Cole, for his part, goes direct 'n' succinct: "Gossip Gossip, [dude] just stop it."

Rubber-faced comic

Jim Carrey

sounds almost serious in a video love letter to

Emma Stone

posted on his website (Jimcarreytrulife.com).

"I think you're all the way beautiful," Carrey tells Emma, who at 22 is 27 years his junior.

"Not just pretty but, you know, smart and kindhearted." Sex is mentioned, but Carrey keeps the weirdo vid PG-rated. He tells the Easy A beauty he's bummed by their age difference. "If I were a lot younger I would marry you. We would have chubby little freckle-faced kids," he says.

"We'd laugh all day long and go camping and play Yahtzee and tell ghost stories by the fire."

Speaking of celebs' celeb love,

Friday Night Lights

alum

Kyle Chandler

, 45, husband since '95 to

Kathryn

, says he digs

Julianne Moore

, albeit in a thespianic manner. "

I've been in love with her since

Boogie Nights

," Kyle tells USA Today. (Would it cheapen his love if we note that JM spent much screen time in that drama nude and in the throes of porn sex?)

Fame, of the girls tearing out their hair at the sight of him type, has eluded Kyle. "I'm not recognized too much. I think I'm recognized enough by the industry."

Ashton Kutcher

, 33, appeared on

David Letterman

's Wednesday show in a police riot helmet and a bulletproof flak jacket that read, in big type, "NOT DAVE." Ash told his host, "You can't be too careful sitting next to a guy that's been fatwa-ed," referring to a radical Muslim jihadist's recent exhortation that David have his tongue cut out for mocking al-Qaeda's top leaders.

Star Wars

alum

Carrie Fisher,

54, says she has lost 50 pounds in nine months on the Jenny Craig diet, which she shills as a paid endorser, USA Today says. The 5-foot-1-inch actor and author has gone from 180 to 129.8 pounds. She has issued a challenge: She'll don that weirdo-but-sexy bikini Princess Leia wore in

Return of the Jedi

if "a whole bunch of women over 40 come to Yankee Stadium. We'll put everyone in metal bikinis, and we will sit around and laugh . . . about the old days when we ate a lot." Fisher's biggest challenge? "I'm at war with my chest. I have exhausted the alphabet on bra sizes and had to go to Sanskrit."

. . . women in power?

Wow

. Forbes' list of the 100 most powerful women in the world this year is topped (again) by German Chancellor

Angela Merkel

. Secretary of State

Hillary Rodham Clinton

is runner-up.

Michelle Obama

is No. 8, while beloved tea party muse

Michele Bachmann

is No. 22. As for the pop-cult lot,

Lady Gaga

is No. 11,

Oprah

No. 14,

Beyoncé

No. 18, and

Angelina Jolie

No. 25.

X Factor

boss

Simon Cowell

, who is said to have an irony-tinged, cold persona, wants to get even colder: Reality TV's Darth Vader tells GQ mag he wants to be frozen when he dies, so that when cryonics tech is more advanced, future generations can microwave him back to life.

"It's an insurance policy," Cowell tells GQ.

"If it doesn't work, it doesn't work. If it does work, I'll be happy." As will all humanity.

"I thought I lost 'boobage' from having a baby," says

Farrah Abraham

, 20, the teenage mother who starred on MTV's depressing reality show

Teen Mom

. A single mom with few apparent prospects, FA gave birth to daughter

Sophia

in 2009. She tells Us Weekly she has regained her bust thanks to breast implants, reportedly bought with her MTV paycheck. (I mean, who needs a crib, baby clothes, or baby food?) "My implants are doing wonderful. I get compliments Literally All the time :)," she recently tweeted to her plastic surgeon.

Entertainment Weekly says country megastars

Faith Hill

, 43, and

Tim McGraw

, 44, will be immortalized as

Barbie

doll effigies in honor of their 15th wedding anniversary. Well, we imagine Tim will be

Ken

doll-ized. He'd look a bit off as Barbie. Info:

» READ MORE: www.barbiecollector.com/

.

Kim Kardashian

won't be getting a star on the Hollywood Walk of Fame any time soon. Fact, none of the reality star's brood will be thus honored:

Ana Martinez

, veep for media relations and producer for the Hollywood Walk of Fame, writes on the Walk of Fame's Facebook page, "Someone asked if we give reality show characters stars? Hell to the No!" Ouch!

Jason Bateman

and wife

Amanda Anka

(

Paul Anka

's daughter) are expecting their second baby. . . .

The Talk

cocreator

Sara Gilbert

, 36, and her partner, TV producer

Allison Adler

, 44, have split up. They have two kids,

Levi

, 6½, and

Sawyer

, 4. . . .

Christopher Knight

has filed for divorce from

America's Next Top Model

winner

Adrianne Curry

.