from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An inferior fighter in the sport of boxing; The insinuation is that an up and coming fighter takes on a “tomato can” to burnish his reputation and record.
- n. A boxer who “takes a dive” or loses a fight on purpose.
Presumably because of tendency to bleed when battered, tomato juice leaking from a can being a metaphor for bleeding. (Wiktionary)