Possible Clues:

• Like a gut reaction?
• That's a funny sort of gadget - can you stomach it?
• It sounds like a grand illusion, but you'll be able to stomach it
• Scrag, it could have caused this ulcer!
• Could one stomach such deception, by the sound of it, with the gas?
• Abdominal wind an illusion, they say
• Sounds like a joke played with what may be fired into the stomach
• To do with the stomach
• Perhaps digest of the funny device of the conjuror, by the sound of it
• That trick sounds great for the stomach