PHOTOS: Justin Bieber exposes his butt, passionately kisses Sofia Richie during getaway to Mexico

                                  
Justin Bieber and Sofia Richie are celebrating her 18th birthday in Mexico with a lot of swapping spit, cuddling  and even a little nudity.

Sofia Richie, who is Lionel Richie's daughter, turned 18 on Thursday and the two got on a private jet Friday headed for the romantic Mexican hot spot of Cabo San Lucas.

Clearly in the throes of young love, Justin Bieber and Sofia Richie couldn't keep their hands off of each other as they showered each other with kisses while wrapped up in each other's arms.

Justin didn't seem too shy to show some skin either. Young man dropped his knickers while standing right next to a butler. See the photos below.


                                
                                 

                                           
                          

                                         
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