Don’t say anything to them unless it’s positive and out of respect. Talking trash does two things. Either you’ll look like a fool because you will end up losing the game or you’ll win without class. If you’re good, you’ll shine with greatness, other people will do the talking for you. The best and most respected players don’t need to talk trash, their game play does all the talking for them.
Of course if you do talk trash you have to back it up: