How to find a game of Munchkin?
Look for stores that sell board, CCG, or role playing games.  I'd start with store finders on sites like Wizards.com. If you don't have a specialized hobby store, you can try more general stores that sell that product type such as Hastings. People at these locations might know other players, or even have places set up to play / hang out.

Check sites like Meetup and Facebook for board game groups. Also check any local universities for that type of group as well.  Sometimes you have to dig, but there are gamers out there!