How to leave the enemy going "WTF?"

So earlier today I was playing Nunu, not well, but not horribly. Due to this there were two players on the other team trying to tilt my team. Fast forward to the end game chat, I said "Have a good life," the player then responded with "WTF?"

So glad that league has reached the state where brushing off an insult is unheard of enough to confuse the crap out of someone :P