The members of the two bands became great friends after touring Europe together and would often play pranks at gigs.
Rocker Christy told Sunday Life: “It’s probably the best memory I have in the music business, touring with Stiff Little Fingers. It was f*****g brilliant — they’re just great.
“We were playing in the Ulster Hall, and during Alternative Ulster in their gig, we all walked on stage in our boxers and started feeling up the band just to wind them up.
“The next night we were playing and our big song at the time was This Is, so we’re on stage and I’m just starting to introduce it (when) Jake Burns from Stiff Little Fingers came on and started Alternative Ulster.
“We might as well have just walked off the stage because the audience went mental and our gig was over then. We had good craic.”
Dubliners Aslan, best known for their hit Crazy World, scored six number one albums in the Republic, with all but one of their 10 releases landing in the top 10.
They have enjoyed a huge following in Northern Ireland for decades, and Christy can’t wait to play in west Belfast next Friday.
He said: “I f*****g love playing the North — there’s something about it. I think it’s because during the Troubles you were all deprived of a lot of music for quite a long time. It’s like people appreciate it then.”
Their show at the Devenish Complex, part of Feile an Phobail, kicks off an all-Ireland 40th anniversary tour that includes a show in Derry in September.
Christy (61) said there would have been no Aslan had he not put on hold plans to emigrate to Australia in the wake of the Stardust nightclub fire in Dublin, which claimed 48 lives.
He added: “The day after, myself and my missus... she had a sister living in Sydney, so we said we’d go over.
“We spent a couple of months over there. Anyway, when we were over there, I f*****g loved it.
“I thought, ‘This place is amazing’.
“She was only my girlfriend at the time — she’s my wife now — but I said, ‘We’ll go back to Ireland for a year, go back to Australia, get married, have our kids and live our life over here. My wife is still sitting here with the suitcases packed 40 years later.”
It was a sliding doors moment that set him on the roller-coaster showbiz journey he has been on for the past four decades.
“Throughout my career, I’ve had goals, and on the way to those, some little incident has happened and it just takes your career on a totally different direction,” he said.
One such example came when he and Finbar Furey duetted on Green Fields of France for RTE’s The Late Late Show five years ago. The clip went viral and has since racked up nearly 14 million views on YouTube.
Christy said: “That’s what I’m talking about — little things that were incidental, then they take on huge significance.”
While the last 40 years have felt like a “flash” he is still reinventing himself, having released a solo album only months ago, so don’t expect him to retire anytime soon.
Aslan are playing the Devenish Complex as part of Féile an Phobail on Friday, March 11.