Sentence:  For years mechanical refrigerator salesmen have delighted in sticking their finger down inside the <WSD>drainpipe</WSD> of an ice refrigerator and drawing it out covered with slime, in an effort to demonstrate to the housewife that ice refrigeration is unclean. 
Meaning of the word marked with <WSD> tags:  A pipe that is part of a device or appliance for carrying away waste fluid.