Nyquil is a medicine that is used to help you sleep when you have a bad cough and/or cold. Some people use it like alcohol. Not a good idea.

This is a medicine that can be misused. Calling it a chaser is a joke. The person would call it that because if is silly to refer to the medicine as a shot. If they really want a drink or shot, few would drink this if there was any other option for a drink.