When I was a child, and my dad told a story about something that happened before I was born, he used to say,
"That was back when you were just a twinkle in my eye."
I really liked the thought of being a twinkle in his eye. I didn't know what it meant, really. I took it literally. (Wow! I was a twinkle once! How does that work?) And then as I got older, realized the impossibility of this, and yet still I thought this was a magical expression.
It's still one of my favorites. (Especially in this economy.)