Celebrity Butts

Lady Gaga was the victim of a drive-by butt pinching Tuesday afternoon in New York ... but don't worry, the assailant was none other than her boyfriend, Taylor Kinney.

Gaga was leaving her apartment in midtown Manhattan when she decided to stop and sign a few autographs for fans. With her back turned, Kinney came out behind Gaga and made his move ... catching her ass totally by surprise with the ole pinch-and-move.

Jennifer Lopez and her mother were cruising through Manhattan when it happened -- our camera guy got the magical shot that proves Jenny from the block ... is also a chip off the ole one.

And Mama Lopez has all the proof (and junk) we need (in her trunk).

Jennifer Lopez and her mother were big hits walking the streets of Manhattan yesterday, and if you didn't know they were related ... a quick pan down of our camera revealed the family resemblance.

J. Lo and her mother, Guadalupe were shopping on Madison Ave. where they encountered a bunch of fans ... including one woman who joked she was happier to meet mom than J. Lo.

Jenny does talk to us about where she used to get her hair did -- but, honestly, it was hard to focus due to the view of mother and daughter butt ... and their shared DNA.

These stars have squeezed their backside into some of the luckiest yoga pants ever made... but are you good enough to look beyond the butt and guess the owners of these tight fitted tushes?

Audrina Patridge is like a way hotter version of the groundhog ... who just poked her barely covered butt up out of the sand -- and good news!

It's officially bikini season. AP's ass said so.

Kim Kardashian jetted off to Paris to get ready for her upcoming wedding to Kanye West ... and when she landed photogs got a giant surprise ... in the shape of Serena Williams' bubble butt.

Serena and Kim hooked up for the Greatest (Ass) Show on Earth ... oh, and also because S-Dub’s probably a bridesmaid.

Mel B looked like a Yukon miner on a digging expedition ... going in fist deep for SOMETHING.

Mel was all dolled up in Beverly Hills Monday for an outdoor photo shoot when she quite literally got her panties in a bunch. The question ... what is out of sorts?

A. Her thong
B. Errant poop
C. Her Shirt

The first option is plausible, but let's not jump to conclusions ... yet. The second is super questionable.

The third option is the most compelling -- she probably tucked her shirt into her skirt and did a simple pull-down.

Serena Williams showed off a little skin yesterday, frolicking in the ocean and enjoying the glorious weather of Miami.

In the battle for the best butt around ... advantage Williams.

These are the Rihanna photos you've been waiting for your whole life -- down on all fours and bottomless. BOOM GOES THE INTERNET!!!

RiRi was posing for pics in the Hollywood Hills yesterday as part of a photo shoot for a French magazine ... wearing some kind of bikini top and nothing else. To make it even hotter, there was even a guy whose job it was to pour water down her back.

The "no touching" rule did NOT apply for this lap dance -- Lady Gaga shoved her ass in her boyfriend Taylor Kinney's face Friday in NYC ... and his hands were EVERYWHERE.

Gaga -- wearing fishnets and a thong bodysuit -- went full stripper on the "Chicago Fire" star inside 42West's new nightclub BPM. We're told Kinney even spanked her.

A source in the VIP area tells TMZ, Gaga showed up with Kinney just after midnight, and the two were all over each other pretty much the whole time.

Don't stop. Let's party.

Katy Perry's got an unlikely new BF -- rapper Riff Raff -- at least that's on Riff Raff's wish list ... because he's SMITTEN after the two went on a date last week ... despite his obvious addiction to other women in thong bikinis.

Raff was out in Miami Tuesday when we asked about his date with the "Dark Horse" singer -- Raff says he took Katy out for the Holy Trinity ... sushi, bowling, and drinks ... and he had a blast.

If Katy's down -- Raff says he'd love to see her again ... maybe next week when she's back in the country.

We're a little surprised though -- Katy's a busty woman ... and from this clip, it's pretty clear Raff's an ass man. You gotta see it.

"Bad Girls Club" star Stephanie Rivera loves big butts (she cannot lie) ... telling TMZ she plans to get a big new ass to go along with her big new boobs.

Rivera says she's going under the knife Sunday in Miami for a Brazilian Butt Lift -- a process in which a doctor sucks fat out of her abdomen, back and love handles ... and then injects it into her derriere to give her a sexier, hourglass shape.

Stephanie -- who recently got her B-size breasts augmented to full C's -- says she couldn't get the shape she wanted by working out ... so she's getting the BBL to take care of her excess flab and her sorry-ass ass at the same time.

Her doctor -- Michael Salzhauer -- tells TMZ, "Curvy is the new sexy," ... and says JLo, Kim K and Nikki Minaj have the butts women ask for most.

Fun fact: Salzhauer says more than 10,000 U.S. women got BBLs last year ... and about 5% of his patients are men.

SF 49ers star Patrick Willis knows what he likes ... CHICKS IN THONGS ... and he went after it hard on a beach vacation to Australia.

Willis -- along with former NFL linebackers Takeo Spikes and Carlos Emmons -- are on a boys trip Down Under and decided to go searchin' for ass on Bondi Beach.

Good news -- they found it.

While Willis was able to pull off the 2-on-1 all by himself, Spikes and Emmons teamed up to chat up two other thong'd up ladies who were catchin' some rays.

Every winter birds fly south and smoking hot models -- like Paz Cornu and Karina Jelinek -- fly north to Miami Beach to tan every last inch of their bodies ... asses AND ass cracks included.

See, winter ain't so bad after all.

Record temperatures in Miami this week -- after these two Argentine models scorched the beach ... wearing these ridiculous thong bikinis.

Miley Cyrus likes big butts (and she cannot lie) so of course she would hop up on stage and join a group karaoke rendition of the Sir Mix-a-Lot classic "Baby Got Back."

Miley took a Bangerz Tour break and stopped into Cat's Meow, a karaoke joint in New Orleans.

A few girls were up on stage doing "Baby Got Back" when Miley jumped up on stage to join them ... and immediately turned around and showed off the goods.

The question is ...