Seven the Hard Way was a Pat Benetar album, and it's a (sort of) reference to the game of craps. "The Hard Way" in craps is rolling doubles - so, Ten the Hard Way is a pair of 5's. (It is twice as hard to get 2 5's as a 4 with a 6). But, you can't roll "Seven the Hard Way" - there's no way to roll doubles and get an odd number!
From the Pat Benetar Fan Club:
"Seven albums in seven years...
Two dice...3½ dots each.
Seven the hard way."