I'll keep working on that brain power

Cust: Do you have the books they sell at the farmer's market?
Me: I'm not sure. What books are they?
Cust: The ones they sell at the farmer's market.
Me: I'm afraid I just don't know what books they're selling at the farmer's market.
Cust: You don't?
Me: Sorry.

I would like to be omniscient. Not this week. Maybe next?