I used to work behind the bar in the Masonic Hall in Portadown, a common request was for a vodkey wi a dash of brown (vodka with some brown lemonade) or for a 'low flyer wi a dash of brown' (a famous grouse with some brown lemonade).
I remember one old boy who had gone over to visit his daughter,who was at university in England, being very disgruntled that the bar man didn't know how to deal with his request for a low flyer wi a dash of brown. His main annoyance wasn't necessarily that the bar didn't stock brown lemonade but that he was forced to buy a whole bottle (mixer) of lemonade. This was a real bone of contention in the Masonic. I used to work in another bar in the town, and the Masonic locals called it a poofters bar because they didn't give you a dash of lemonade but forced you to buy a whole bottle.
Perhaps a dash is a uniquely Northern Ireland thing I don't know, but it is dying out, as is brown lemonade. I think brown lemonade is also available in some parts of the States though. I have been told it's just normal clear lemonade with a touch of molasses if anyone wants to recreate it.
Also the term lemonade is used a lot here in my part of the world for any fizzy drink. I think this stems from the lemonade man (Braid or Maine) who delivers all manner of fizzy drinks to your door step, sasparillo, pineappleade, splice, red lemonade.
This train of thought got me thinking about those uniquely Northern Irish products, we used to have Soda Bread and Potato Bread, but Paul Rankin now packages them up in brown paper designer packaging and flogs them for 1.20 a farl in Waitrose and Sainsburys.
I think we still haven't sold out with our Veda. Although it appears to have been repackaged and exported as the link shows, I haven't seen it on the mainland though.
We also have the usual tayto crisps, dulce (seaweed) and yellow man (honeycomb), but are there any other uniquely Northern Irish products I can't think of any.
On another note my mate who works a lot in England was asked by one of his colleagues to think of a stunningly beautiful woman from Northern Ireland that would be well known on the mainland, this has stumped us for over a month. We tried our best with The Corrs, one of them is often dandering round Stranmillis, but we can't lay claim to her. Mary Peters, Gloria Hunniford. Both lovely women (and from Portadown aswell) but not exactly stunners to the younder generation.