I bet you never knew ___________, what exactly?

Yeah, any random piece of information, on any subject whatsoever that you believe isn’t, as of yet, common knowledge. Basically unknown to the majority of people.
However trivial, no matter how nerdy & inconsequential it may sound. Any examples of the “hidden gem” which actually has at least some point of interest attached?
I shall offer my example, if only to clarify my intent.
I bet you never knew (or cared) that there are 10 times as many coconut related deaths per year than there are shark related fatalities!! Weird huh?