"Craic" is an Irish word of broad ideomatic use in Irish English.
On its own, the word means "fun" easy good times, traditionally at a pub in the evening.
"What's the craic" means "How're you doing."
"How was the craic" inquires about a social experience.
"Great craic" describes an occasion.
"The craic was 90" is the superlative, apparently. There's a song about it. Nobody knows what it means.