Onomastics
The name is related neither to the popular MGM cartoon characters nor to the earlier Tom and Jerry cartoons by Van Beuren Studio, nor to famous bartender "Professor" Jerry Thomas, the author of one of the first bartender's guides, How to Mix Drinks (1862). Instead, it is a reference to Egan's book, Life in London, or The Day and Night Scenes of Jerry Hawthorn Esq. and his Elegant Friend Corinthian Tom (1821), and the subsequent stage play Tom and Jerry, or Life in London (also 1821).
To publicize the book and the play, Egan introduced a variation of eggnog by adding ½ fl oz of brandy, calling it a "Tom and Jerry". The additional fortification helped popularize the drink.
Read more about this topic: Tom And Jerry (mixed Drink)