Norman walked into Flourish and Blotts, excited. He loved books: big books, small books, fictional books, nonfictional books, muggle books, but more than anything, he loved not just books that teach magic, but books that use magic! He looked at his Hogwarts list.  All the books he needed were in the front of the store.  That gave him time to find other books. Back home he was the Prankster. Any time anyone needed a prank pulled, a trick trifled, or anything of the sort, he was the go-to man.  It was who he was. But at Hogwarts, who knows, he could lose the title he oh so dearly loved and enjoyed. But to keep it, he had to up his game. No more muggle-style escapades. No, he needed magical ones. But he needed something to teach him the ways of Wizard practical jokes. He needed a spellbook purely devoted to the joking arts. Unfortunately, he had no clue where to find one. But he was in Flourish and Blotts, the wizarding bookstore. If they didn't have any, nowhere would (except for maybe broom-azon).  He approached the person behind the counter.

"Do you have practical joke books?"
"Yes, why?"
"uhh..." Norman couldn't say it was for Hogwarts, the man most surely would be disdained.
The man smiled, "For Hogwarts?"
"Yes." Norman said sheepishly.
"I think we have a couple books in the back, let me see what I can find."

The man was back there for over a minute before he responded. "Found one!" Norman smiled, his legacy would continue at Hogwarts. The book was called "Nifty Curses and Hexes to Help at Hogwarts."
He opened it and saw spells ranging from Pretrificus Totalus to Rictemsempra, the tickling curse. He smiled and asked "How much?"
The man replied, "That's my last copy. I don't know how long i've had it back there. At least five years. Take it, you'll put it to good use." Seeing Normans shocked face, he continues. "Besides, the price tag is so worn it doesn't even have a price on it anymore."
Norman was so pleased as he paid for the rest of his books. He wondered why the man had been so willing to give it away. As he finished paying, he found out.
"You know, when I bought that book, it came in a pack of twenty. Only two people who bought that book weren't expelled. So a word of warning: use it few and far between. Never in classes. And even then the jokes will have their own price. That is one of the reasons I gave it to you for free." The man smiled, the conversation was over.