Have a huge sale on all of the final four memorabilia you had to have just 48 hours ago.
Talk to everyone you know about the game as if you were an expert. This includes mocking the refs calls, stating how unfair the other team played, and sympathizing with each player.
Start recognizing the other teams on campus and possibly attend a game of theirs. Some examples of these sports that are less acknowledged include swimming, tennis, field hockey, lacrosse, rugby, frisbee, ultimate frisbee, extreme ultimate frisbee, golf, frisbee golf, extreme ultimate frisbee golf and of course quidditch.
Start becoming a fan of the team that beat you. You will be banished from your school and deemed a fair weather fan for all of eternity.
Watch the finals and cheer on the team who DID NOT BEAT YOUR TEAM! Remember, your opponents opponent is your friend. Or in this specific instance, the team you cheer for and hope ruins whoever beat you.
Wait a week, then forget any knowledge of basketball you probably never had and go on living your life.