You're telling the system to use one of the built in voices to say the word "Droid".
There's a number of them out there. Here's a list of a few I found. Just add whatever word you want to the end of the string.
say -v Albert
say -v Bahh
say -v Bells
say -v Boing
say -v Bubbles
say -v Cellos
say -v Deranged
say -v Hysterical
say -v Trinoids
say -v Whisper
say -v Zarvox