We, as a culture, are rich in euphemistic variations on the theme of balls in the meaning 'courage, guts', etc. Cajones seems, for instance, to be widely accepted and used. And we get a kind of euphemistic ellipsis pretty often, like in the usually sarcastic: "Must be hard to walk" [with balls that big.] A common part of that these days (no idea on the age of it) is variants on to grow some balls, etc. Last night's Daily Show, in fact, had a good example, graphically illustrated. See here.
In the context of increasing Democratic, oh let's say, "resolve", Ed Schultz today talked about somebody having "the ping-pong balls in his shorts" to get a job done. He later made a remark about ordering some ping-pong balls to be delivered to a particular US senator. I just caught that much, but it sounded like he might be starting a campaign to mail ping-pong balls to Democratic lawmakers.