You put taunts on every single one of your champions.
So in other words:
-Okay for riot to troll and be rude
-Not okay for players to do so
And you can say that the taunts and jokes were put in for entertainment value, but in practice people use them to be annoying just as if they were saying rude things in chat, Only difference is that its harder to get away from Riot trolling you than it is your average player.