Justin Bieber and girlfriend Sofia Ritchie show massive PDA on vacation in Mexico

Singer Justin Bieber and his new girlfriend, model, Sofia Richie were in the romantic Mexican hot spot of Cabo San Lucas on Saturday to celebrate Sofia's 18th birthday, where they put on extreme PDA while lounging in their bathing suits by the beach. The young couple couldn't keep their hands off of each other as they showered each other with kisses and at one point Justin Bieber seemed to have a visible erection. More photos after the cut..