The phrase "to be someone's favorite color" means that a particular shade or hue is preferred by an individual over all other colors. This could refer to a person's personal preference, which may have been influenced by their experiences and memories associated with the specific color. For example, if a person grew up surrounded by blue skies and clear waters in their childhood home, they might develop a strong affinity for that particular shade of blue. The phrase can also refer to an emotional connection someone has with a certain color, which could be influenced by cultural or societal associations. For instance, the color pink is often associated with femininity and love, so someone may choose it as their favorite color because it evokes positive feelings for them. Ultimately, "to be someone's favorite color" means that the specific hue holds a special significance to the individual and brings them joy or comfort when they see it.