
Lady Gaga jams with Mick and Keith, a Beatle goes helter-skelter with Dave Grohl, and Rihanna hangs out with—Jim Parsons?! Plus, more of the stars’ best tweeted photos.

Lady Gaga became the newest Rolling Stone this week at rehearsals for Saturday’s pay-per-view concert, where she joined Mick, Keith, Ronnie, and Charlie onstage for a rendition of “Gimme Shelter.” “Me with the boys,” Gaga wrote. “When rock and roll gets you wet in 6.”

Portlandia star Carrie Brownstein’s dad sure looks proud at the premiere party for the show’s third season. “So grateful for all of the dear friends and guests who attended the Portlandia premiere. Me w/@allsongs and my dad,” Brownstein wrote.

If Mindy Kaling’s desperate, single character on The Mindy Project were a book, she would definitely be called Microwave Cooking for One. “World’s saddest and funniest prop,” Kaling wrote.

In this week’s edition of Bizarre Celebrity Pairings, Jim Parsons and Rihanna posed for a sweet, black-and-white picture together while in the studio lending their voice talents to the upcoming DreamWorks Animation production Happy Smekday! “Worked with the very talented Jim Parsons today #animationLife,” Rihanna tweeted.

Rita Ora and Cara Delevingne practiced some black magic at a party this week, with the singer writing, “I put a spell on you… and frank lol.”

First a duet with Taylor Swift, now an Instagram shot with Ryan Seacrest—looks like British singer-songwriter Ed Sheeran is hitting the big time. The two made wacky faces in a photo that Seacrest simply titled, “@edsheeran.”

Who wouldn’t get this excited if they found themselves in a room apparently constructed entirely out of Christmas trees? Nick Cannon got down in Mariah Carey’s bunny slippers while Carey snapped a picture and wrote, “Nick sneaks a peek by the tree in MY bunny Lamb slippers.”

R&B crooner Miguel, a mainstay on nearly every critic’s "Best-of-2012" list, ran into a familiar face while touring in Toronto: Michael Kenneth Williams, a.k.a. Omar Little from The Wire. “The homie happened to be shooting a film in TO when we played there last week,” Miguel wrote.

Don’t trust the b---- in the studio, Jesse Tyler Ferguson! Krysten Ritter and the Modern Family star posed for a picture together—and made a mock baby announcement. “It’s true! We are a couple with a baby on the way!” Ritter wrote.
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Arguably the best thing to happen to Twitter this week was the addition of Dean Norris to its ranks—or, as he’s better known, Hank from Breaking Bad. Mostly so far, Norris’s tweets have been a hysterical mixture of dad jokes and Breaking Bad references (his second one read: “Asked Cranston fr twitter shout out. He leaned in, went Heisenberg and said “I AM THE ONE WHO TWEETS” dude is method”). Norris also tweeted a baffling photo of himself in a bat-car, on a bat-phone, in the middle of a street and wrote, “Same Bad time. Same Bad channel. KAPOW! Hank using the batmobile to catch Heisenberg.”

30 Seconds to Mars frontman Jared Leto tested out some new material on loyal listener and friend Terry Richardson. Judging from Richardson’s thumbs-up, there’s good stuff on the way. “@terry_richardson listening to UP IN THE AIR for the first time. He gave it a thumbs up! #terryrichardsonstudio,” Leto wrote.

Paul McCartney stood in for Kurt Cobain and played with Dave Grohl, Krist Novoselic, and Pat Smear at the 12-12-12 Sandy benefit concert last week and, as captured in this photo of helter-skelter Paul (and Grohl’s tiny, floating head in the background), knocked his own socks off doing it.