Chug a lug is an onomatopoeic expression that describes the act of rapidly drinking a lot of liquid in one go. If you're looking for synonyms, you could try "gulp", "quaff", "swig", or "down in one". Other options include "chug", "chug down", "chug-a-mug", and "drain". All of these expressions can be used to describe the action of consuming a lot of liquid in a short amount of time. So whether you're taking a shot of tequila or downing a pint of beer, there are plenty of words you can use to describe the act of chugging it down.