Another stupid conjoined word for a famous Hollyweird couple. It is the combination of Tom Cruise and Katy Holmes. Also, when Katy Holmes became visibly pregnant, her belly and the fetus within it were known collectively as the TomKat Bump.
The very current couple otherwise known as Tom Cruise and (formerly) Katie Holmes. These two were in the spotlight for most of '05, during which they met, became a couple, and got engaged. They are now expecting "TomKittens", and will be married either in the summer or fall of '06.
TomKat were recently visiting Kate's parents, but left 3 days early due to some issues between Tom and Kate's father.
In fighting sports, a tomato can is a fighter with low skills who is brought in to pad the record of more promising fighters and give them more ring experience. They are expected to lose. Most professional boxers of any note have dozens of wins in their early careers over tomato cans. The name is believed to come from the fact that tomato cans "leak" red fluid (blood) like a can of tomato sauce.