Is it normal my 4YO talks about ghost and killed people all the time?

From experience i know several foreign exchange students in my class who genuinely speak and write this way, their English tenses are not exactly eloquent, not to mention their accents. However, I can still understand them perfectly. I've seen how they are harassed and ridiculed for it by pompous american students with their perfect english, with such statements similiar to yours "you can barely speak properly.." etc

Your first response did two things; if for one this was indeed a troll which you assumed, then you did "feed the troll". Wouldnt your "correct action" have been to simply ignore it, not even bother with such trolls?
Second no need for the extensive introductory definition of a troll. Simply saying the word "troll" would have sufficed.

But by all means copy and paste from Merriam Webster as much as you please...