Dickinson opens this poem with a somewhat surprising statement, especially for our world of "15 minutes of fame": "I'm nobody." Then she asks the reader or someone to whom the poem is addressed the question: "Are you nobody too?" Whomever is being spoken to must answer in the affirmative, because she notes that there's a pair of them, and she adds, playfully, that they should tell because they'll be banished for being nobodies. Alread the poem is ironic: who would both banishing a nobody? And why does she seem to happy to be nobody?
The answer comes in the next stanza.
How dreary to be somebody!
How public, like a frog
To tell your name the livelong day
To an admiring bog!
Being a somebody is being just another somebody. The comparison to a frog is telling. You might think that the frog belongs to the "nobody" since it doesn't make the most flattering simile. And look what a somebody does: the "tell" their name. Telling and name are an interesting choice of words. It almost sounds like the croaking of a frog: I'm here, see me, pay attention. And of course, look who their audience is: a bog. Definately not a favorable description of the audience that is reenfocing them.
So, ironically, it's better to be "nobody," to be your OWN nobody, than to be the somebody who tells his name all day to get the reenforcement they need.
This poem reminds me of Emerson's Self-Reliance. Croaking for attention with the rest of the frogs will never make you an individual; only being a "nobody" will.