Probably the most toxic thing I've ever seen typed was just said to me in post game chat.
I legit had someone tell me in post game chat that they wish my firstborn to get leukemia and told me to go eat a pencil sharpener. That is probably the most toxic thing I've ever seen in the 4 years I've played this game. "KYS" and "go kill yourself" don't even hold a candle to telling someone that you hope their firstborn child gets cancer.