To Black Bird's shock, you and Rainbow Dash kick open the door to your cell having won the game, flown up from the dungeon to the room of the ruins she's in, and you invoking Royal Protocol to arrest Black Bird for marenapping a national celebrity. And flying in the other direction of a designated flying zone. Despite all protests that you started it by mailing a shipment of candy onto her house, Rainbow blows it off - you actually used Black Bird's bank details for the purchase, but nopony else needs to know.
Frustrated at her revenge having not stuck, Black Bird decides it's time to get serious - she pulls out what seems to be a souped-up Mark V Party Mini-Cannon from her mane and decides to just bubblegum you and Rainbow to the floor. She fires and manages to bind you to the wall, but Rainbow is just swift enough to dodge in time, grab three more Party Cannons of her own, and try to fight back.
However, just as the two of them are about to engage in what must surely be the least harmful duel of the century, you hear a knock on the door, and Black Bird goes to answer. At the door is an extremely crotchety old grey stallion, who's just come round to complain about the noise. However, you can see that he's decided to deal with his extra nosy neighbours personally and with extreme prejudice - for he too is carrying a Party Cannon - Mark VII, he must be tech-savvy for an old fogey.
Suddenly Rainbow, Black Bird and the grumpy old neighbour find themselves in a truel. As per prank war tradition (it exists, for Celestia knows what reason) when two or more individuals with Party Cannons gather in one place with disagreements hanging in the air, the matter must be settled with a turn-based shoot-out. Each of you will take turns using a Party Cannon to blast one another, going in a circle - Rainbow, then Black Bird, then the old guy. That means Rainbow is going to have to choose one of the three party cannons she gathered up before, pick one of them, and start playing. Black Bird, with a hint of pride, mutters out loud she hits seven out of ten times. But the old grey pony who ain't what he used to be can hit a pony nine times out of ten.
Black Bird and Old Fogey, as you nickname him, allow Rainbow first shot, as the one with the worst aim. After some sulking over the blunt insult, you just tell Rainbow to get on with it. So, what is she going to do?
Out of the Party Cannons Rainbow grabbed, one is the Mark II which jams about 40% of the time, one's a more modern Mark IV with a jam rate of 20% and then there's the Party Rocket Launcher 2000, which will without fail generate a party for the whole family to not enjoy.
It IS worth noting however that each Party Cannon ever manufactured does come with a certain clause: after one round, if everypony is still gum-free, all the cannons are primed to explode and coat everything in gum. And cake batter. And balloons. As per standard procedure for exact situations like these, you understand.
So what should Rainbow Dash do to ensure that she has the best odds of making it out the duel without getting gummed?