When someone say you suck!
I just agree with them and then there is no more flaming by them. It so easy, it all a bunch of mind game. It like they can talk trash further but it lead nowhere since I'll just agree with them. Obviously to do this you need to have a laid back personality like myself but it really take them by surprise and it kind of fun.
For the record, I am a very good League players so the time I do get flame is extremely rare and for the most part I just ignore toxic people.