Possible Clues:

• Grow stale like still water
• Bungling agents receiving little thanks get really foul
• Become foul from inertia
• Although fed around the North, the buck may be still in a bad way
• In a particular phase belt up and become inactive
• Lapse into inactivity
• Remain in a rut
• Just sit
• Beast with a 10 inclined to suffer from immobility
• Must a gnat evolve features to resemble pond water?