The craic is mighty. Irish slang is storytelling in miniature, every expression sounds like it belongs in a pub tale. Grand, deadly, gas, the Irish make three words do the work of thirty.
Shenanigans
Shenanigans are playful mischief, dodgy carry-on, or sneaky goings-on, depending on how cheeky the situation is. Kids get up to shenanigans, dodgy salesmen are up to shenanigans, and a wild night out is full of them. The word itself sounds like trouble having fun, which is exactly what it covers.
Banter
Banter is the back and forth of playful teasing between mates, quick witted jabs that land as affection rather than insult. Good banter keeps a group lively, the slagging flying both ways with nobody really hurt. It can tip into bad banter when someone takes it too far, but at its best it is the glue of a good friendship.
Blagger
A blagger is someone who talks their way into or out of just about anything, all front and smooth patter with not much behind it. Half con artist, half charmer, they will blag a free upgrade, a backstage pass or a job they are barely qualified for. You half admire the nerve even as you clock the act.
Culchie
Someone from the countryside, basically anyone who isn't from Dublin, said with varying levels of affection depending on who's saying it. If you're a Dubliner it's a mild jab at country folk. If you're a culchie yourself it's a badge of honour. The word is often linked to Kiltimagh in Mayo or to the Irish word for woods. Either way, it's pure rural Ireland bottled.
Boke
To vomit, or the feeling that you are about to vomit. Can also describe something so disgusting it triggers that response. Covers the full spectrum from actual physical sickness to pure emotional revulsion at someone's behaviour. Scottish and Irish folk use it daily and it sounds exactly like what it describes, which is part of its charm. One syllable, maximum impact.