We have a treat for Green Day fans: three previously unheard demo songs that were recorded before Dookie. Reportedly these tracks are from around 1992-1993 or so, after the release of Kerplunk in '91.
The fan site Green Day Authority say the demo tape contains early versions of ‘J.A.R.’, ‘Having A Blast’ and ‘Don’t Wanna Fall In Love’.
Give it a listen:
And while I'm skeptical, the YouTube link claims that "even the band does not seem to know about [the demo's] existence."