If you're going to AFK and ruin someone's placement matches, don't come back and say 'kys'.
Seriously, two of my three placement matches had an AFK in them.
I wouldn't be so angry if they didn't say 'kys'. That escalated them from a simple report to an email to riot support.
When I told the player what I did, only then did he get apologetic. Once I told him I'd already sent the email, he said to kill yourself again.
Yeah okay, buddy. Enjoy the review.