Selena Gomez' Instagram is sizzling with racy photos lately! What has happened to the 'Come and Get It' singer? First she posted an almost nude photo of herself behind a sheer curtain and now she posted a bootylicious picture. She was standing in front of the mirror wearing a sheer top and extremely short shorts. She captioned the photo as 'Secret project'. I'm sure that got many people wondering what her secret project is.

Ever since the couple reunited, there seemed to be a Justin Bieber and Selena Gomez Instagram showdown. The YouTube sensation also showed his sexy side by posting a photo of him wearing a button-down shirt and underwear. He posted together with the photo, "What if I do a Calvin Klein campaign? Comment below yes or no." I'm sure the Bielebers will be thrilled to see Justin wearing a sexy boxers.

The celebrity couple's showdown of hotness doesn't stop on Instagram. An insider told HollywoodLife.com, "He gets plenty from her and has a slew of pictures and videos of her that would make the Internet explode."

The source added, "He gets all the important stuff to him for himself." No wonder Justin isn't complaining about his girlfriend's racy pictures. He must have kept all the good stuff that Selena gave him.

Since the lovebirds are busy with their careers, the only way they can remain closer to each other is through social media network. The insider also revealed that Justin and Selena send each other nakes pics and even do intimate things on Skype. I don't have to get into detail with that one.

The Selena Gomez Instagram and Justin Bieber underwear photos may also be a marketing strategy. With the songstress saying that she has a secret project, then there could be a chance that the two will be working on an underwear campaign together. Do you think that they will be the perfect models for Calvin Klein?