No clue what this Pin is for - Gas station? Hotel chain?

This is a very old looking pin that I found going through things that belonged to my Grandparents.

The '78' is prominently displayed and at the bottom of the pin is the wording "GRREAT IN" GRREAT in what???

I'm not sure what to categorize this item as....will probably need to be moved once someone can help identify what it is. I tried googling with no decent results. I put it in advertising for now.