I could say I am something of an expert on hyenas. In another life, when I used to earn a living as a naturalist, in simple terms, a person who studies plants and animals as they live in nature, my boss instructed me to popularise the hyena.
The chap was an old game warden prone to wild and ribald jokes. Thinking he was spinning a new one, I said, “You are killing me!” and laughed hysterically like a hyena. Turned out this one time, he was serious.