My attempt at 88:
Jack, Google "Jill" now. Jill, Google "Jack" now.
Google "Jill" now, Jill. Google "Jack" now, Jack.
Jill, now Jill, Google "Jack". Now, Jack, Google!
Now, Jill, Google "Jack". Now, Jack, Google "Jill".
Jill, Google "Jack" now. Jack, Google "Jill" now.
Google "Jack" now, Jack. Google "Jill" now, Jill.
Jack, now Jack, Google "Jill". Now, Jill, Google!
Now, Jack, Google "Jill". Now, Jill, Google "Jack".
I'm thinking that speaking and names might lead to a longer one. But I agree with Deusovi that the "natural" sound of some sentences is subjective.