In the context of the poem what does blue skin most closely mean? in the story masks

This poem is a She Silverstein poem called "The Mask." Silverstein's poems often teach a lesson or explain childhood situations. Often this poem is invoked with a meaning of self-acceptance "be your true self because there are other people just like you, and you'll never know that if everyone conceals their true ways of being." Sometimes, it is invoked to promote people being accepting of others, because we all have a version of metaphorical "blue skin." Taken yet another way, it can even evoke the meaning of shared knowledge or revealing a secret that is concealed. In the end, this poem underscores, self-acceptance, acceptance of others, and shared knowledge: openness in all of its forms. A beautiful poem and meaning.   

Sorry ,but i would need more information