It's often remarked that the best English in the world is
spoken by the Irish, but that is patently untrue. The language spoken by
the Irish is barely comprehensible to English speakers from other parts
of the world.
So full of colloquialisms obscurities is our version of
the language that an outsider would probably need a degree in linguistics
before they would understand what the hell we're trying to say.
In the absence of that, let us be of some assistance to you. Here is the
IrishAbroad guide to Irish slang.