View source for Android/DeveloperOptions

# Go to the settings menu, and scroll down to "About phone." Tap it.
# Scroll down to the bottom again, where you see "Build number." (Your build number may vary from ours here.)
# Tap it seven (7) times. After the third tap, you'll see a playful dialog that says you're four taps away from being a developer. (If only it were that simple, eh?)
# Keep on tapping, and *poof*, you've got the developer settings back.