OK not many people know how to properly deal with trolls, so im gonna help you all.
first things first, piss the guy off as much as possible, and keep going until he is either resorting to spamming, or is speechless, then say/type these words:
LMAO im pwning you so bad you [insert any insult here]
just type that after everything he says, it has never failed me, not even once. after you do it a few times, you can change it a little bit, to not look like spam, and if he calls you a troll, just quote something dumb he says and go back to typing what i said, continue this until he gives up, they always will eventually, you just have to have commitment to debunk him.
and a helpful hint, dont restrain yourself by using logic! trolls almost never use logic, so you dont have to either, which means, you dont have to make sense as long as it pisses him off.
hopefully this will help somebody, because im fairly sure it wontyou