“That’s three Galleons, nine Sickles, and a Knut,” said Fred, examining the many boxes in Ron’s arms. “Cough up.”
“I’m your brother!”
“And that’s our stuff you’re nicking. Three Galleons, nine Sickles. I’ll knock off the Knut.”
“But I haven’t got three Galleons, nine Sickles!”
“You’d better put it back then, and mind you put it on the right shelves.”
Ron dropped several boxes, swore, and made a rude hand gesture at Fred that was unfortunately spotted by Mrs. Weasley, who had chosen that moment to appear.
“If I see you do that again I’ll jinx your fingers together,” she said sharply.

Harry Potter and the Half-Blood Prince – J.K. Rowling