Ever heard/read something & thought to yourself "How interesting, how have I lived __ years without having this tidbit of knowledge embedded in my brain! I must let the world know so that other may not know this emptiness and inconvenience I have endured for so very long...."
Anything interesting - not necessarily just random facts, but useful knowledge. Stuff around the house, how something works, a somewhat familiar word you finally looked up in the dictionary, "common sense" bestowed upon you by an elder, etc.. basically, any tip or hint that could better someone's life forever (or just make them smile).
Don't let the world go without this bit of knowledge! Only YOU can prevent ignorance!