Rules:
- Over 30 years old
- Should be a HUGE hit everyone in your country remembers to this day
- Preferably something that is relatively unknown outside of your country
- Preferably sang in your native tongue
Rules:
There are so many good ones for Austria. Probably have to go for Fürstenfeld by STS. I have never met somebody in Austria who wasn't able to sing this, even (or especially) when drunk.