When a person does/says something to get a particular outcome, or to manipulate a situation, of their desire that usually affects an innocent party in a negative way - usually in the situation of causing arguements amoungst friends/in relationships. There also usually is no clear motive for such actions; they may not even dislike the said victim.
"Ted: Oh My God, I can't believe Tess told him that!
Todd: I know, and Trudy didn't even mean it in that way!
Ted: What a CSB!"