Unless I totally missed that day of class, DWV systems are not pressurized therefore not subject to water hammer.
Generally, water has to be flowing for a noise to happen unless there is something living in your pipes. The only case I can think of is a freeze-thaw cycle going on in a relatively flat run in the dwv if the water is not flowing. If your nick means what I think it means, there ain't no freezing going on where you are
Not a pro so this is a layman guessing.