Related Clues:

• Shock to the system
• Catch off-guard
• Sudden impact
• Make the hair stand on end
• High-caffeine cola
• Caffeine's kick
• Rude awakening
• Hit with a haymaker
• Say "Boo!" to, say
• Give a fright
• A bit of a shock
• Big bump
• Shock somewhat
• Eye-opener
• Suddenly spook