Unexpectedly funny

My sister actually heard this, but she hasn't put it on her blog yet so I'm going to.

We were in a parking lot. She was just coming back to the car, where I was waiting. A family was walking the other way, toward the store entrance. The lady suddenly bent down and said, "Look, a dime!"

Then she commented, "I've been finding dimes all the time lately. I found one yesterday too."

Then she said, "If I had a dime for every time I found a dime..."

And didn't realize how funny that was until she'd said it.