There are numerous synonyms for the phrase "tossing back." Some of the most common options include gulping, chugging, drinking, swigging, sipping, and imbibing. All of these words refer to the act of taking a drink, typically of an alcoholic beverage. Other synonyms for the act of tossing back a drink could include quaffing, knocking back, downing, and chugging down. While these words may have slightly different connotations, they all refer to the same general action of drinking quickly and in large quantities. Overall, there are many ways to describe the act of tossing back a drink, depending on the context and the specific word choice of the speaker or writer.