Not a saying per se, but still Iowa bred:
Kum & Go
First time I came across the Campustown convenience store, I thought "Wait, that can't be right, can it?"
Try 'splainin that one to out-of-staters....
If you think that's good, there's a c-store in Rochester, Minnesota called - no kidding - Pump 'n' Munch. Cracks me up every time I drive by it.