In the link listed further up are just some slang words explained, but not the meaning of the whole song.
If it is just about visiting a cinema what means the first verse and why they are talking about a church and all those people in Dublin? In the first verse the narrator seems to be nervous, I do not think that it is just the fear about someone under his bed. So why is he really nervous? The song said Dublin has changed since the pillar was going down, what does that mean?
Perhaps I am thinking about it in a complicated way, but if it were just a song about a cinema then there would not be such infomations about the church, the people (bang-bang) and the narrator himself.