Despite pointing out to him that actual facts and history disagree with his assertion, he claimed that there wouldn't need to be incentive, for money would be non existent, and you are rewarded for your work you did for no money by having a right to what other people did for no money, and vice versa.
Communist economies still rely on outside trade. Even if you did achieve "World Communism," paper currency would simply be replaced with goods and services, and there would still be people who delegated it out to "each according to his need."
I've said before that every country is capitalist. It just varies as to holds the capital. If the concern of communist is for workers to not be exploited, there are a number of ways that can be achieved through a capitalist society.