During the breakfast with both couples, what does Elyot say that sparks the fight between Victor and Sybil?

While Amanda is talking about traveling, Elyot makes a rude joke about the perils of eating foreign food. Victor is offended, but Sybil tells him that he does not have any sense of humor. In response, Victor makes a few snide remarks about Sibyl, which finally causes the tensions that had been building between the two of them for the last few days to spark.