So I was WRONG.
Birthday Girl was outside and missed the conversation with her Grandpa.
It went something like this:
"So Rachel called and said your Great Uncle Roy (who is 92 and lives in a house that is slowly sinking into the cistern it was built on) needs a new flush. And won't pay for it. Old people don't like to spend their money and so she called me to go look at it.
I told her I'd just clear a path to the old two holer."
Birthday Girl's oldest sister sat smirking at me, with her back to Grandpa.
Then we both asked at the same time, "What's a two holer?"
"It's an outhouse with two holes," he said.
"What do you need two holes for?"
He didn't answer, but instead offered this: "In the old days sometimes they even had three."
It's a real shame she missed this. It was the best Grandpa story EVER.