Ginger in disguise
A ginger in disguise is a redhead with pale skin and freckles, who dyes their hair a different color in order to lighten persecution.
Person 1: did you hear? Alex dyed his hair black.
Person 2: Really? Well I guess he's a "Ginger in Disguise"
Person 2: Really? Well I guess he's a "Ginger in Disguise"