Inishowen refers to whiskey or, more likely, poitín made in the north Donegal peninsula of Inishowen. It's mentioned in several songs, among them "The rollicking boys around Tandragee" where there is a line - 'And sweet Inishowen for a drop of the pure'. Poitín making was a regular industry in the area, to the extent that, in 1812, after one part of the Parish of Clonmany was heavily fined for its production, a number of townlands to the north-west of the Parish declared themselves a republic, barricaded the only road, over the Gap of Mamore, that led into the area at that time. The 'Poitín Republic of Urris' lasted until the British were able, in 1815, to spare troops to invade it, which was accomplished without resistance. It is still, to an extent, a place apart, even within its own Parish.

I know of other songs with reference to Inishowen spirits but need time to look them up.