Rule #3 - Never be unreachable.
When McGee was late, and couldn't hear his cell phone ringing with calls from NCIS, we learned about Rule #3. Contrary to popular belief, it's not, "Don't wear turtleneck sweaters," though there is actually another official Rule #3 - "Don't believe what you're told. Double check."
Watch NCIS Tuesdays at 8/7c.