2 ways to deal with retards.
1st is bigdaddy's way.
"When game is going full retard, you can only go with it.
If you start going against it, if you start going half retard, you´re f***ing done for."
-n0tail 2014
Just continue trolling with the and go with the flow.
or 2nd, ignore trolls and just play your own game. Be patient and try not to flame,
There's this recent game which I played with my friends, there was a fat ursa and dagon 5 bot blink tinker on the opposite side, bottom racks is down, we only manage to take 3 t1 tower and they took all our t2.
Somehow we manage to turtle and win team fight after team fight as they got very careless/arrogant and made mistakes after mistakes because they were so far ahead in the game which eventually turn the tide around and we won that game.
Sometimes miracles happen.