Carolyn,

Michael Scott, the obnoxious lead character on the American version of "The Office" referenced Bulgaria in Season 2:

Dwight Schrute: That suit is amazing.

Michael Scott: Thank you very much, it is from Italy-- actually [checks inside of blazer] no, Bulgaria.

You're right, once you notice, Bulgaria does get referenced quite often because, frankly, no one really knows anything about Bulgaria let alone where it is. On a related note, do you think Walla Walla gets referenced in pop culture as much as Bulgaria?

It's mentioned in Bugs Bunny cartoons. Even Woody Allen referenced Walla Walla in one of his films. I believe it was something like, "Bora Bora? I wouldn't know Bora Bora from Walla Walla!"