This thread's for people who know useless information or want to learn new useless information. Just spout out something you know that you think few other people will/do. Try to make it something interesting--something worth mentioning randomly around your friends. (source your trivia if you can; also, if you "already knew that," don't waste our time saying so)
I'll start. Apparently dog breeders cannot breed two Mexican hairless dogs together, because if an embryo has two dominant alleles for hairlessness, it'll die. They instead breed Mexican hairless with a hairy dog, resulting in half being hairless and half being hairy, but none being dead. (source is my heredity book, Human Genetics Concepts and Applications Tenth Edition by Ricki Lewis)
Also, the letter "J" doesn't appear anywhere in the Periodic Table of Elements.