"Percy: I shudder to think what the state of my in-tray would be if I was away from work for five days. Fred: Yeah, someone might slip dragon dung in it again, eh, Perce? Percy: That was a sample of fertilizer from Norway! It was nothing personal! Fred (whispering to Harry): It was. We sent it."
Book: Harry Potter And The Goblet Of Fire Will it ever not be funny to send people pieces of dragon excrement to their workplace? Probably not. To be perfectly frank, Percy deserves it, and he is the only person in the world who would manage to appreciate it and actually sprinkle it on his lawn.