On the Town:Ian Fitzgibbon, director and co-writer of the film, said they had "a fantastic time making it" when it was shot in Dublin last February.
To be entering the big league with their first feature-length film, in comparison to their early days, is "very strange", he said. "In some ways it feels decades ago, and in other ways it seems very near."
Michael McElhatton and he met in London's Royal Academy of Dramatic Art in the 1980s, and work together using improvisation, he said.
McElhatton says Rats, the hapless lead he plays in the film, "is a character I've had in my head for years and years". As the film opens, Rats is being released from Mountjoy Prison.
"He's a lovable loser and quite a complex character for all his simplicity and delusions," says McElhatton.
Among the hundreds of guests at the première in Dublin this week was portrait painter James Hanley, who attended Terenure College in the early 1980s with McElhatton and could recall him playing the lead in King Lear. "He was brilliant," he said.
In the star-studded Irish comedy, Donal O'Kelly plays Brainer, a gay keyboard wizard who is in love with Keith, played by Simon Delaney, of Bachelors Walk fame.
"We rob a boyband of their costumes so we get to shimmy around in white silky military tunic-style costumes," he said, paying tribute to costume designer Kathy Strachan.
Broadcaster Miriam O'Callaghan, who has a cameo role in the film, was at the Irish première, as were actors Peter McDonald (who plays the long-haired Tommo in the film) and Tomás Ó Súilleabháin; electrician Máirtín Ó Tuairisc, from Connemara; singer Maria Doyle Kennedy; former film censor of Ireland, Sheamus Smith; and comedian Tommy Tiernan with his girlfriend, Yvonne McMahon.
Spin the Bottle is on general release