With new diseases.
Explanation: This joke is a darkly humorous take on a tragic historical reality. When Columbus and other European explorers arrived in the Americas, they brought diseases like smallpox, which devastated Native American populations who had no immunity to them. The punchline plays on the idea of “greeting” as something positive, but instead of a friendly welcome, Columbus’s arrival led to the unintentional spread of deadly diseases, making the joke a commentary on the harmful consequences of European colonization.