Possible Clues:

• Emphatic refusal, one for Blair: rule only when reformed
• Less than a century unacceptable
• Socially unacceptable, whichever way you look at it
• Weightless? Impossible
• "--- your life!"
• Informally, cannot be permitted or tolerated
• Colloquially, cannot be tolerated or accepted
• It's impossible whichever way you look at it
• Unacceptable, whichever way you look at it
• Impracticable either way