I was just looking at the verb to be (here) and I saw the subjunctive form "I be". Other than pirates saying "I be looking for treasure" I couldn't think of a single usage of "I be". Not knowing what subjunctive meant I went and looked it up but now I'm left thinking that "I be" could never be used in a grammatically correct way.
If I understand correctly the subjunctive form is for an irrealis mood which implies that the speaker doesn't know if the action or situation has happened as they are speaking. Surely that makes any sentence starting "I be" a logical contradiction - the speaker must know whether the action has started as they are doing it? Perhaps that is the humour behind the sentence and I'm just the last one in the room to get in!