Xenophon's Laughter

Aristas, who was a terrific eater, the Greek word there is kind of funny. He grabbed in his hand a loaf as big as a three quart measure. He put some pieces of meat on his knees and he proceeded to dine. They carried round horns of wine and all took them. But Aristas, when the cup bearer came and brought him his horn, then after observing that Xenophon had finished his dinner, give it to him for he's already a leisure. When Sufi heard the sound of his voice, he asked the cup bearer what the man was saying. So there was an outburst of laughter. And I still can't quite figure out what's funny about