Kim Kardashian took to her Instagram at approximately 9:20 a.m. (Pacific) on Tuesday to show off her six pack and just a smidge of underboob after she "Just finished [her] morning workout." She also shared a photo from her first Mother's Day, showing off the ginormous wall of flowers fiance Kanye West gave her, which towers over daughter North.

Justin Bieber took in some horseback riding in the Hollywood Hills on Monday, riding a "pure bred (sic) stallion" and captioning a selfie, "Is that young Indiana Jones?"

The singer also shared a flashback photo from when he was a toddler, hanging out with mom Pattie Mallette, writing, "Happy mothers day mama and all the other Amazing mothers out there."

Supermodel and current one-third of the Sports Illustrated Swimsuit Issue cover girl trio Lily Aldridge shared a super-sexy, droolworthy shot of herself in a black lace lingerie one-piece; while Alyson Michalka, the sexy half of singing duo Aly & A.J., shared a hot bikini shot of herself.

Soap star Kelly Monaco also joined in, pushing the limits of what Instagram allows by sharing a topless and near bottomless photo on a beach chair trying to erase her tan lines, and then doing a little monkeying around. "Blahhhh #vacation (i'm not naked)," she captioned her pretty naked shot.

Pro surfer Anastasia Ashley added to her myriad bikini shots, sharing three recent shots on her way to hang 10; Khloe Kardashian showed off a slim figure; and Ice-T's voluptuous wife Coco also pushed Instagram's boundaries, showing off about 97% of her flesh in a teeny, tiny white bikini (which is pretty NSFW and near the end of the slideshow, above).

Lastly, "The Big Bang Theory" star Kaley Cuoco also monkeyed around on set when she was transformed for last week's episode of the hit show. You know, the one where she she gets engaged to Leonard (Johnny Galecki) and the show officially begins its jumping of the shark, which will be completed once the big wedding occurs.

Speaking of weddings, UFC Ring Girl Brittney Palmer was married over the weekend, officially taking her off the market. She posed with pals Arianny Celeste and Lauren Rachel.

See them all and more in the sexy celeb Instagrams slideshow above!