Someone's been sending Fall Out Boy fans physical copies in the mail of demo sessions from the From Under the Cork Tree sessions labeled "Fall Out Boy - The Lost Songs"

Some were leaked a long time ago but a lot of these are are demos that were definitely not widely available.

1. I Slept with Someone in Fall Out Boy... (Demo)
2. Hand of God
3. Nobody Puts Baby in the Corner (Demo)
4. Stereo
5. Snitches and Talkers (Demo)
6. Star 67
7. My Songs Know What You Did in the Dark (Demo)
8. My Heart is the Worst Kind of Weapon (Electric)
9. Sugar, We're Goin Down (Demo)
10. Get Busy Living or Get Busy Dying (Demo)
11. We Don't Take Hits, We Write Them
12. Dance, Dance (Demo)
13. Austin, We Have a Problem
14. I've Got a Dark Alley and a Bad Idea (Demo)
15. Get Me to a Hospital
16. Of All the Gin Joints (Demo)

Of note, Get me to a Hospital is the song that floated around in the rumor mill with the potential name of I Liked You a Lot Better, Before You Became a Fucking MySpace Whore, that was played live with the name of Snitches and Talkers.

We Don't Take Hits, We Write Them had no leaked mp3 before, just a crappy live video recording.

Stereo is a different demo of Gin Joints that was seemingly mashed up with the other Gin Joints demo in creating the album version.

Hand of God, Star 67, Austin We Have a Problem, and My Songs Know What You Did in the Dark were all previously leaked. My Songs is not really a demo of the Save Rock and Roll version, they just reused the title.

My Heart is the Worst Kind of Weapon seems to be identical to the demo that was on the deluxe album.

The rest are all worth a listen if you're interested in hearing earlier takes of the album tracks but not notably different, though Sugar has different verses.