Synonyms for the phrase "knocks back" generally refer to consuming or ingesting something, particularly a drink or alcohol. Some common alternatives include: drinks, quaffs, gulps, sips, swallows, imbibes, indulges, tosses back, and bottoms up. Each of these options carries slightly different connotations- for example, "indulge" implies a greater degree of enjoyment, while "toss back" suggests a more casual, carefree approach. Other potential options could include "downs," "takes in," or "partakes of." All of these terms are useful for describing the act of drinking- whether it's a quick shot of whiskey or a leisurely evening spent sipping cocktails.