You can stop calling me bitter now.
For a series like this, there needs to be a consequence that directly involves you. Some measures involve more risk than others, but the payoff is a heavier investment and less doubt in your mind on what side to take. Here's a few suggestions in ascending order of severity.
National Pride
A quick and easy solution is to go the way of
Potential Conference Final Matchups
Some playoff series are just more entertaining than others. Something like Penguins/Flyers is always going to better than the Minnesota Wild vs. anyone. It becomes ten times better if it's the third round. However, due to the nature of statistics, probability, and playoff seeding, you will never get your desired finals matchup. Ever.
Tattoo Bet
Someone I know actually has one of these going. If Toronto wins the Stanley Cup before Montreal does, he has to get a Leafs tattoo. This is a bonafide way to ensure you never cheer for a team again. If you're a Flames fan, call up an Edmonton or Vancouver buddy, and get set up. Having to pay money for such a shameful mark on yourself might not be something you want to do, but there's no way they'll ever win it ahahahaha right? Right?!
Suicide Pact
Why are you doing this? Seek a psychiatrist!