Lady Gaga teamed up with legendary crooner Tony Bennett to sing at a private event for Obama's staffers.

The eccentric performer, who wowed in a white Versace dress, belted out "The Lady Is A Tramp" alongside Bennett at the Washington Convention Center.

When President Obama hit the stage, his staffers reportedly sang to him ... "Signed, Sealed, Delivered."

Looks like it was quite the night!

Lady Gaga performed at the Staples Center in Los Angeles over the weekend, and the pop superstar seemingly had more costumes than she did songs on her set list! We're used to this by now, but when will she stop putting more of a focus on her wacky wardrobe than her extraordinary vocal talents?

"Thank you for letting me feel like the cool kid in Hollywood," Gaga told the crowd at the end of her show. "I'm a lucky girl ... Everybody raise your glasses to a brand-new album, a brand-new tour and a brand-new year." We're still not sure when Artpop will hit stores, but we're guessing Gaga will make an announcement soon!

And as expected, Gaga also set tongues wagging with her skimpy attire:

Lady Gaga and her little sister spent five hours getting tattooed at Shamrock Social Club in West Hollywood over the weekend, and we're not sure what she got this time around, but we're guessing she'll share a snap on Twitter any minute now!

In other news, it's being reported Gaga is looking to pull a Lana Del Rey and make the transition into movies. "She's decided to go from a pop star to a movie star. Gaga thinks that if she gives up the crazy rock 'n' roll lifestyle, Taylor [Kinney] will propose," an insider told the National Enquirer. "Gaga is actually a traditional girl and wants to settle down."

The tabloid also reports that Gaga is planning on winning an Oscar within the next five years! Hey, it's always good to set goals, but if her first major film role is going to be in Robert Rodriguez's Machete Kills, she might not want to put such a strict time limit on things...

And the fighting continues!

Kelly Osbourne has been engaged in a very public war of words with Lady Gaga recently, and now mom Sharon is speaking her mind on the cat fight.

Kelly O has taken shots at the pop star for years, first calling her a "Butterface" in 2009, then slamming her weight in September, saying, "I think she is pregnant." It is the British beauty's obligation to critique celebrities and their outfits for her hosting job on Fashion Police, but the "Born This Way" singer's fans aren't having it!

Millions of "Little Monsters" have been posting horrible things on social media about Osbourne, who spoke out about the cruelty in Fabulous magazine last October, saying, "Lady Gaga's fans are the worst. They've said I should kill myself, that they hope I get raped. I mean it's crazy but I've had this all my life and I just try to ignore it."

Gaga replied by posing an open letter to Osbourne on her blog Thursday.

"I have empathy for you Kelly, but I feel it culturally important to note that you have chosen a less compassionate path. Your work on E! with the Fashion Police is rooted in criticism, judgment, and rating people's beauty against one another... What about your body revolution? It used to make me truly sad when I would hear people talk about your weight when you were younger, as I was bullied too. To see you blossoming into a beautiful slender woman who makes fun of others for a living is astounding," she wrote.

The America's Got Talent judge is now coming to her daughter's defense, calling on Gagaloo's manager to urge the Grammy winner to dissuade her fans from all of their bullying.

"Your open letter is hypocritical and full of contradictions. And as your mother Cynthia supports you, I support my daughter Kelly. I am calling you a bully because you have 32 million followers hanging on your every word and you are criticizing Kelly in your open letter. Are you so desperate that you needed to make this public? A word from you will stop all the hideous, negative, and vile threats from your 'little monsters'" the family matriarch posted to her Facebook page.

Your move, Mother Monster!

We love her music and her voice, but her wardrobe has gone from eccentric to absolutely ridiculous ... sorry!

When she's not planning another silly outfit, she is taking the stage by storm, as evident from her set with the Rolling Stones over the weekend.

Gaga tweeted a video of their performance of "Gimme Shelter" and wrote, "Can't wait to sing with the Rolling Stones on Saturday Night. In 2007 i was stripping to them ... PAY PER VIEW did a stellar job with the SOUND, the mix was insane on TV they sounded immortal!"

Check it out below!

Lady Gaga and wild animals go together like peas and carrots!

The pop singer recently enjoyed a safari while on tour in South Africa, and she could barely contain her excitement over the diverse wildlife she got up close and personal with!

"SAFARI PICTURE: in this photo I'm about 10 feet from 13 lions, 2 cubs. I spent about 30 minutes w them and took a nap," she captioned the above photo.

Gagaloo even modified her bush hat so her ponytail could stick out! She doesn't skimp on style, even in the Sahara! The Grammy winner donned a scarf that was a gift from the Princess of Monaco!

Mother Monster is scheduled to perform a concert in Cape Town tonight, and we have a feeling her safari might influence some of her onstage costume selections!

Lady Gaga is showing us that "Cake" is finger-licking good.

The 26-year-old songstress has released yet another teaser from her upcoming video for the single "Cake" ... directed by her friend and famed fashion photographer Terry Richardson.

In the hyper-sexual clip, Lady G is wearing stiletto heels while writhing around on a table in a pile of icing. Of course, she has to lick her fingers which are full of cake.

The clip ends with Gaga in the bathtub wearing nothing but a G-string. Just another day for the eccentric singer.

We can only imagine what the rest of this video is going to be like!

Lady Gaga just released a teaser for her latest song "Cake," and because it's directed by Terry Richardson, we knew it was going to be on the wacky side! Shot with a night vision lens, the clip shows Mother Monster dirty dancing with girls and parading around in lingerie as she practices her dance moves and rap skills.

The pop singer debuted the tune during a Mugler fashion show back in September. The lyrics are feisty, with verses like, "You chew beef, I wear meat/And stay on top of the -- I'm I'm I'm/ Getting fat and so is my bank/With a sold out world tour, b**ch."

Check out the rap!