to the person above who said the only time they saw people get together and sing was among Irish people, Id say you havent gotten out much. Many of my Czech friends often get together and sing folk songs (Czech ones, or what they call tramp songs) My grandad used to go to the pub daily and often they would sing drinking songs.
Im sure that was fairly common all over central and eastern Europe.

what about fiddle tunes, or instrumental tunes written in the tradition by non-Irish people, or second generation folks like Liz Carroll. Tunes such as Brenda Stubberts (CapeBreton tune by Gerry Holland) which I heard in a Galway session. (As well as other Canadian or Scottish tunes that have made it into the Irish repertoire)