“In addition, it is possible that a collective of Auditors with sufficient presence in the material world may develop crude physical senses, and so I have adapted some catapult bows to fire a mixture of intense, er, stimuli. Old references suggest chili, essence of Wahoonie or Blissberry blossoms, but modern thinking inclines to HIggs & Meakins Luxury Assortment.”
“Chocolate?” said Ridcully.
“They don’t like it, sir.”
“But those things can live in empty space and inside stars, man!”
“Where chocolate is significantly absent, sir,” said Ponder, patiently. “They keep away from it. Also, it comes handily packed. They particularly don’t like the Strawberry Whirl.”
Ridcully picked up a bow, pointed it at a wizard, and fired. There was a distant “ow!”
“Hmm. Spreads nicely on impact,” he said. “Well done, Mr. Stibbons. I’m impressed. You are in charge.”

– I hope Ponder performed the Rite of AshkEnte to ask Death to ask Susan what to do |
Terry Pratchett, Ian Stewart, and Jack Cohen, The Science of Discworld III: Darwin’s Watch