When a complete asshole takes over a private conversation already in progress an ignores one of the people previously in the conversation.
If one does this to his friends, he will soon have none.
Jason is hanging out with Seth and Brad and just talking about whatever. John comes in and starts talking about other shit that Jason isn't a part of, forcing him out of the conversation.
Eventually, Seth and Brad catch on that he is robbing the conversation and they beat the snot
out of John.