Double Vision, Double Punch-line

(It’s early spring, and the city where my parents live received a snowstorm the previous week. I’m on the phone with my parents. People are always commenting that my dad and I have the same sense of humour.)

Me: “So, are you still getting bad weather over there, or has it cleared up?”

Mom: “Oh, it’s much nicer! Your father was excited today because he saw seven robins.”

Me: “Is he sure it was seven robins? Or was it only the same robin that he saw, but seven times?”

Mom: “No, it was seven all at the same time.”

Me: “Is he sure it was seven, or is he suffering from double vision in his old age?”

(My father and I speak the next lines at the same time:)

Me and Dad: “Maybe it was only three-and-a-half birds!”