I really took time out thinking about this topic. It might be a joke, fact, science-fiction, political or social event but it's a fact there are events that happen once in a lifetime. Here are the few I can mention;

¤ USA having a black president.
¤ An African country hosting the World cup/Olympics.
¤ An African being the best in a globally recognized event.
¤ Nigeria having an Igbo president.
¤ Solar eclipses.


Add more up.