Red
Red is a color commonly associated with war and danger, as well as passion and love. Red is a very emotionally intense color which increases heart rate and blood temperature. This is why it is used on danger signs as it gives us symptoms of fear.
Red is often worn to show erotic feelings, but gives of a high-energy emotion, making it great to use to promote energy drinks and high energy activities.
It is als a color used to denotate courage, which is why it is commonly used in national flags.