1. To slow or inhibit forward movement or progress to the point of stagnation and ultimately, death.
2. The act of drawing someone's attention away from something, or to deflect.
3. The polar opposite of helpful.
According to Donald Trump, Hillary Clinton got schlonged by Barack Obama in the 2008 democratic presidential primary. This is akin to getting screwed; slighted; severely whooped; underhandedly beaten; having your ass handed to you ,etc.
She (Hillary) was gonna beat (Obama), she was favored to win (the 2008 Democraticpresidential primary), and she got schlonged, she lost.