Possible Clues:

• Zone which one must not enter
• Region where entry is dangerous, impossible, or forbidden
• Dangerous territory
• Out-of-bounds zone
• Zone where access is barred or risky
• Upset Reagan twice over subject never to be discussed
• Place to be avoided
• It might be barricaded, so you'll have to pee elsewhere
• Head couples to nose — Gonzo's arm's easy section with restricted movement
• Some of M25, now and then?