Green’s Dictionary of Slang

1. a bedbug.

1909

J. Ware Passing Eng. of the Victorian Era.

2. a fool, a victim [mug n.¹ (2a)].

1859		Hotten Dict. of Modern Sl. etc.
1873		Sl. Dict.
1898		Binstead & Wells Pink ’Un and Pelican 208: Ball always looks quite the gentleman. Anyway, he succeeded in making the ‘tom-tug’ think so.
1935		A.J. Pollock Und. Speaks n.p.: Tom tug, a mug; easy mark; sucker; chump; boob.
1946		St. Vincent Troubridge ‘Some Notes on Rhyming Argot’ in AS XXI:1 Feb. 47: tom tug. A mug (sucker). (Origin uncertain, probably American.) Almost certainly English. Tom Tug, a young Waterman, was a popular character in one of Dibden’s operas, c. 1800–1815, with a famous song, ‘Farewell, my trim-built wherry.’.

3. (US) a thug.

1953

Berrey & Van den Bark Amer. Thes. Sl. (2nd edn).