Ok I give up I don’t have any material and don’t feel like preparing any because the influx of IMO problems, including the shortlist, is too fascinating. Instead, here is a joke quoted verbatim from TVTropes (CC-NC-SA).

An American anthropologist has been studying a tribe in Africa by living with them for a year. One day, the chief called him into the chief’s hut. The chief sighed. “Well, my friend, it seems that we must ask you to leave.” The anthropologist was surprised by this; he thought he had gained the tribe’s trust. “Why, what’s the matter?” he stammered. “It seems that a woman in our tribe has given birth to a baby… a white baby,” said the chief. The anthropologist began to laugh. “Oh, is that all? No, that’s just a classic case of albinism. It’s caused by inheriting recessive pigment genes and…” The chief didn’t look convinced, so he pointed at a nearby flock of sheep. “See those sheep? All of them are white except for that one. It’s like that!” The chief was silent for a moment and said, “Listen, you don’t talk about the sheep, and I won’t talk about the baby.”

If you don’t get it (it took me a while), you can Google the phrasing to discover which page it’s from. Good night.

edit: I forgot the most important part, linking to the streak.

(note: the commenting setup here is experimental and I may not check my comments often; if you want to tell me something instead of the world, email me!)