I would fly to Peru to get to hit the Lab Nutrition 'Test Your Strength' billboard -- simple idea that was well executed and is now gaining global appreciation.
The billboard features a circle with a fist in the middle and once this circle is punched, there is a meter at the top of the billboard that tells you how hard your hit was. The brilliance of this commercial is that by the end, you can watch people hit the billboard as they test their strength. The Lab Nutrition Test Your Strength billboard hit hard and left an impression.
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Violent Interactive Billboards
Interactive Nighttime Ads