God I love Big Macs. Big Macs are more American than a damn bald eagle, and more delicious than they are pulmonarily congestive, if only just barely. Here's one on a belt buckle from the 70s.
You don't really need any more information than that, but if you must, here's what the eBay seller says:
This is a limited edition McDonald's brass Big Mac belt buckle. On the back it says Limited Edition and Copyright 1975 McDonald's Systems Inc. It is still in very good condtion.
Ah, the 70s, when America was AMERICA, and we loved fast food so much we wore it on our belts, in brass. Which is wonderful, and also deeply, irreparably horrifying. [eBay]