Sentence:  In Rihanna's new music video for her song S&M, images flash on the screen of the singer being taped to a wall, fondling the plastic while a bunch of reporters look on with disgust. Clips of article headlines flash to the beat with quotes like "Daddy Issues?" as if to insinuate that Rihanna's <WSD>wall-humping</WSD> behavior is a normal form of self-expression and not a result of emotional instability. The fact that teen girls all over the world will watch this video is frightening, to say the least. 
Meaning of the word marked with <WSD> tags:  Gyrating the hips towards a wall in a sexual fashion.