Defender Easter Egg - Programmer's Initials

On Wave 25 of the game, allow an enemy to capture a human. Shoot the enemy and catch the falling human. Don't deposit the human on the ground for points, however. While holding it, move the ship to the 25th horizontal resolution line (slightly above the city--keep moving up and down until you find it). While your ship hovers with the human at this level, any additional enemies will turn into the letters "BP." These are the initials of programmer Bob Polaro.