Over the garden fence

In the garden with my wife today, my neighbour poked his head over and said, "Congratulations to you and Sarah having a baby!”

I laughed it off, "Cheers, mate."

"Alright, mate," he replied and disappeared.

Feeling my wife's angry gaze on me, I said, "Are you upset I told him?"

Spoiler:

"Who the is Sarah?” she screamed.