Brian agus í féin - - Brian and she herself

Do you remember the personal pronouns
mé, tú, é, í, sinn / muid, sibh, iad (as object of the verb) and
mé, tú, sé, sí, sinn / muid, sibh, siad (as subject of the verb.)?
No? You will find them explained here (as object of the verb)
and here (as subject of the verb Tá).

Now you have the meaning of Sinn Féin - - Ourselves!
and the sarcastic "Mé Féin political party" - - The myself party said of selfish politicians.