A colleague of mine complained, "When the home team is winning, they don't bother playing the bottom half of the ninth inning. I'm getting ripped off! Make them finish the game!"
This led to some speculation as to how the visiting team could manage to salvage a win out of that final half-inning, given that they had no further opportunity to score any runs. My proposal was that they could try to get as many players on the home team to be rendered ineligible to play (say, by injuring them or provoking fights and getting them thrown out of the game), until the home team had fewer than nine eligible players, at which point they would be forced to forfeit the game.
Mind you, employing this technique would certainly earn retaliation the next time you faced that team, so it's not a viable long-term strategy. And the league would certainly crack down on this sort of behavior.
It was merely a theoretical exercise.
I consulted with my umpire colleague, and he said that the home team could respond by simply refusing to come to bat. Rule 6.02(c) states that if the batter refuses to take his position in the batter's box, the umpire shall call a strike on the batter. Do this three times, and the batter is out. Do this nine times, and the half-inning is over.
Mind you, the standard way of implementing this rule is to instruct the pitcher to deliver a pitch, and to call it a strike no matter where the pitch lands. But what if the pitcher doesn't want the free strike? Rule 8.04 says that if the pitcher fails to deliver the pitch within 12 seconds, the umpire shall call a ball. Or maybe this is where the umpire can exercise his judgement and call the strike in a nonstandard way. Or the umpire could declare the fielding team to have forfeited for "refusing to continue play during a game", per rule 4.15(c).
(Though there is an interesting conflict between rules 6.02(c) and 4.15(c). If the batter refuses to come to the plate, both rules apply, yet the penalties are different.)
This is all very confusing, what with conflicting rules applying to the same situation, and the umpire will have to improvise, per rule 9.01(c). (My favorite example of umpires having to improvise is the case where a switch-hitter faced an ambidextrous pitcher. At the end of the season, they added a new rule to cover this situation.)
Looking for another loophole in the official rules of baseball, I found another way the visiting team could induce a forfeit: Provoke the crowd into rioting for fifteen minutes, then request that the umpire declare a forfeit on the grounds of inadequate security, by rule 3.18. On the other hand, the declaration is at the umpire's discretion, and seeing as you are the ones who provoked the riot, the umpire is unlikely to grant you that one. (So you'll have to provoke the riot surreptitiously.)