What De Fuck was indeed a joke by Mike because they couldn't come up with a real title for the song. And they didn't record Emptiness either because they only recorded 15 songs for Indestructible, 12 are already on the album and the 3 b-sides (Parasite, Run, Midlife Crisis) have already been released. I don't know about Mine though, my guess is they half-finished that song because on the DVD there are some things they recorded for it, but not everything.