BDD is short for Behavior-driven development. The Wikipedia article on BDD is really long, but as far as I can tell BDD is better summed up as: "When you're writing code, examples are really helpful so you should get as many as you can stomach. If anything is unclear, ask for some more examples."

I don't know if it's strictly in following with BDD, but a lot of the time I ask for examples that aren't like previous examples. That can be pretty enlightening.