This ad grabbed my attention right away on another site's sidebar. It uses the classic "Don't do this unless" hook. Oftentimes, this hook is used to sell something....View More Here, it's used to get people to click. Bottom line, the hook can be used to grab attention & hook people in regardless of what action you want them to take. More than the copy, note how the color is very bright & the word "DON'T" is capitalized & made bigger than everything else. Whoever created this ad understood that the word "don't" is likely to draw attention because it is counter-intuitive copy & represents a warning that you should pay attention to.