Here at local Waffle Houses you can get different flavors added to your soda. They have Vanilla, Cherry, and Chocolate. Maybe another one.
So there you go. Chocolate Coke.
I tried Mezzo Mix when I visited Germany years ago. It's Coke with orange flavoring. It wasn't too bad.
There was also Coke Blak for a while. Coke with coffee. It was okay.