Klindabar. I suppose it's not the worst ever, but everyone at the table thought it sounded like a candy bar. Various jokes were made at the players expense about monsters trying to get to his nougaty center.
There is also our default "random NPC guy" name John Fernow. It came from a DM who was asked what a shop owners name was. He said "Um, I don't know, John ... for now. I'll think of something better later."
Worst ever was completely unintentional. One of my players made a warrior by the name of Darkarius. The name seemed innocent enough when written on the character sheet, but as soon as the player introduced himself everyone at the table started to laugh. We will always remember his dark-hairy-a$$.
