Don't own HP – no really I don't. Italics is directly from the book
"Polished it last night," said Cedric grinning.
Harry looked down at his own wand. He could see finger marks all over it. He gathered a fistful of robe from his knee and tried to clean it surreptitiously. Several gold sparks shot out of the end of it. Fleur Delacour gave him a very patronizing look, and he desisted. HP Goblet of Fire.
"Really, Potter," Cedric said as he came over to the boy, when Ollivander was done with his wand, "you should only clean your wand in the privacy of your room, not out in public." Harry gaped at the grinning Hufflepuff, as he continued, "you could get arrested for indecent exposure if you do that." Harry flushed bright red and looked away, and Cedric snickered at the easily flustered boy.