Sentence:  "If anybody should come in, and catch you with your breeches, as it were, down on the floor, all you have to do is to drink the water, wrap the rubber <WSD>dingus</WSD> around you, and tell them to “lay on Macduff.” 
Meaning of the word marked with <WSD> tags:  A gadget, device, or object whose name is either unknown, forgotten, or omitted for the purpose of humor; a thingamajig.