be too

be too

To be able or permitted to do something. This construction is mainly used for emphasis in short sentences that typically end with "too" or follow "too" with a verb. A: "You aren't allowed to have sweets this early in the day." B: "I am too! Mom said I could, just this once." A: "You guys aren't allowed to be here this late!" B: "We are too allowed! Let us in!"

be too

 and be so
to be something (despite any information to the contrary). (An emphatic form of is, am, are, was, were.) Mother: Billy, you aren't old enough to be up this late. Billy: I am too! I was so! I was there exactly when I said I would be!
References in classic literature ?
Nothing of the kind," answered the Duck, "every one must make a beginning, and parents cannot be too patient.