Gender blur

Tiffy answered a phone call today from her boss' son. He has one of those temporary is-it-a-teenage-boy-or-a-woman voices, calls once a month or so and always says the same thing, "This is Matt. Is my dad there?" My son, on the other hand, calls almost every day, sounds like a man and is not named Matt. Finally, I do not look or sound like a man (in case you were wondering).

Bearing all this in mind, why on earth would Tiff put Matt on hold and tell me that *my* son is on the phone? I took a deep breath and reminded her that Matt was her boss' son and it is genetically impossible for me to be anyone's father. Her response?

"Ohhhhh, I was wondering why he called you his dad!"