Green’s Dictionary of Slang

tommyrot v.

to fool around.

1984

Partridge DSUE (8th edn) 1247/1: late C.19–20.

In derivatives

tommyrotter (n.)

a confidence trickster.

1882

Biography of Cheap Heiress Hunters in Ware (1909) 184/2: Well, these Tommy Rotters kid the poor judy they’re very rich, and if they’re now and never they get carefully carried (married) to her.