Craic means the fun, banter, and general buzz of a night out, or the chat and gossip that comes with it. If something was good craic, it was lively and worth showing up for. You can even rate a person as great craic, meaning they’re brilliant company. Also pops up in What’s the craic? as a casual what’s happening. No craic means a dead atmosphere.
"What’s the craic tonight? Liam’s bringing the tunes and Aoife’s pure gas, so the pub’ll be mighty, sure we’ll have a grand time."