"I walk on two legs. I am not a dog!"
Translation:Ninatembea kwa miguu miwili. Mimi si mbwa!
And that's the whole point, isn't it? We tend to remember better "extreme" examples, those that are odd and require some thinking before we find a context for them. A rebellious youth, refusing his father's request to fetch something from the kitchen could easily reply, in a fit of righteous indignation: "Can't you tell me from a dog? I walk on two legs..." . One of the most hotly debated sentences in linguistics, originally due to Noam Chomsky reads "Colourless green ideas sleep furiously" . So, ours is not that bad, in comparison :-)
These are 2 independent sentences. If you think about it, the reason we exclude pronouns often is because the verb already carries a subject prefix i.e. ninatembea. There's no way to do so for the 2nd sentence. Basically, if you remove the pronoun, does the sentence still make sense?