@riot What am I supposed to do when this happens, and how can I try and get this person in trouble?

I hopped into a ranked game and I was in champ select, when the first thing I see is someone saying that they are going to intentionally feed. The person then starts arguing with someone from a previous game, saying that he is going to intentionally feed to reduce stress and that the other person deserves this. I was unable to report this normally, as someone dodged because he locked in teemo jungle with cleanse and barrier.