Brew (or probably Bru from Irn Bru) is likely to work anywhere in Scotland, but you'll probably only get Irn Bru using that phrase.
Irn Bru outsells Coca-Cola in Scotland. IIRC, it's the only country in the World where Coca-Cola isn't the number one soft drink.
Ginger (which I originally thought would mean Irn Bru only - due to it's recognisible colour) actually applies to any carbonated beverage and seems to be a phrase local to Glasgow.
If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.
That way everyone learns.
