Here in Northern Ireland (and the Irish Republic), we have a lot of sayings, phrases and words that are mainly/only heard here.

Examples:

"Norn Iron": "Northern Ireland".

"Quare": "Very". Pronounced like "where" but with a "k" at the start. "That's quare craic, so it is!" meaning "That's very good fun, for sure!"

"Craic": "a good time" (sometimes bad). Pronounced "crack". Mostly used to describe social situations such as parties or nights out. "Good craic" and "great craic" are two to describe fun times, but if everything was amazing, it could be described as "the craic was 90".
If someone asks you "What's the craic?" they're asking "What's up?"

"So it is" is used as affirmation. For example "That movie's brilliant, so it is!". There's also "so he is" and "so she is". Then "so they are", "so it was" and "so he did".

"Yer man" or "yer girl". When referring to someone. Example "Give that box to yer man over there." meaning "Give that box to that man over there." When we refer to women up to a certain age, we call them a girl. Not in a demeaning way, mind you! 

"Wee" means "small" or "little", but not always used in that way. Imagine you're in a shop. The cashier will likely ask you "Do you need a wee bag?" or "Put your wee card in the machine."(insert your bank card into the reader). Often the word is used multiple times in a sentence! 

"What's yours"? means "What's your order?" in a bar, takeaway or somewhere you place an order, though not in more "formal" places.

"You gettin'?" means "Are you already being served?" 

"Supper". When you go into a chippy (fish 'n' chips takeaway) and order a fish supper, you're getting fish and a good-sized scoop of chips. Applies to sausages, battered sausages, *pasties and other things. The term is also sometimes used in England, Scotland and Wales.
*https://en.wikipedia.org/wiki/Pastie 

"Whaddabout ye?" or "'Bout ye?" means "How are you?" 

"Houl yer whisht" or "Houl yer wheesht!" means "Shush!" or "Shut up!". It's hard to describe how "houl" is pronounced. Also used in Scotland.

"Jammy" means "lucky". Example "Some jammy sod just won that car!"

"Dead on" can mean a few things. Example: "Aye, dead on!" is similar to "Sure, Jan."  Alternatively "She's dead on!" as in "She's really nice!" or "It's dead on!" meaning something is pretty good, example "This bicycle's dead on!"

"Melter" means someone who is annoying. "He's a melter, him." meaning "He's really annoying!" 

"Give my head peace!!" means "Go away and leave me alone!" or "Stop bothering me!"

"Head showered". Means to clear your head. Example "I'm away to get my head showered." or "I'm going to clear my head."

"Head felt" means need/s to see a psychiatrist. Usually when someone's being weird. Example "You need your head felt!" meaning "You're weird!" 

"Keep 'er lit!" means "Keep going!" or similar. Encouragement.

"Dander" means a walk. Example: "I'm going for a dander to the library." meaning "I'm going for a walk to the library." or "I'm away for a dander." meaning "I'm going for a walk."

"Hoke" means to scoop out/rummage/root. Example: "The cat was hoking in that box." or "She's hoking in her handbag." 

"'At's us nai!" means "That's us now!" or "mission accomplished" or "job done!"

"Taps aff!" when lads take their shirts off, usually on the rare occasion we get a warm, sunny day!

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So what about you?