What was that?

"Throw the ram down the hill, yes," the man repeated hopefully.
The Doctor frowned: "No, I don't understand."
"You don't know what is a tongue twister?"
"Yes, something like: 'He threw three free throws.'"
"That's not a tongue twister. How come you speak Czech so perfectly, but you can't get this?"
"Ah," the Doctor stretched to flip a switch. "Say it again."
"Cože? Sej it egen? Co to je?"
The Doctor frowned, probing his memory: "Znovu rekni."
"Shoď z kopce skopce."
"I see," the Doctor flipped the switch. "Now, what was the point?"
"I don't know," the man grinned.
"Oh..."