" Demon pox, oh demon pox
Just how is it acquired?
One must go down to the bad part of town
Until one is very tired.
Demon pox, oh demon pox, I had it all along—
Not the pox, you foolish blocks,
I mean this very song—
For I was right, and you were wrong!"

"Will!" Charlotte shouted over the noise, "Have you LOST YOUR MIND? CEASE THAT INFERNAL RACKET! Jem—"
Jem, rising to his feet, clapped his hands over Will's mouth. "Do you promise to be quiet?" he hissed into his friend's ear.
Will nodded, blue eyes blazing. Tessa was staring at him in amazement; they all were. She had seen Will many things—amused, bitter, condescending, angry, pitying—but never giddy before.
Jem let him go. "All right, then."
Will slid to the floor, his back against the armchair, and threw up his arms. "A demon pox on all your houses!" he announced, and yawned.
"Oh, God, weeks of pox jokes," said Jem. "We're in for it now. "

― Cassandra Clare , Clockwork Prince (The Infernal Devices, #2)