I believe the slices of bread was a story told by Tom Petty whom Brian was having dinner with. If I remember correctly (??) this story is in the book "Beach Boys: In Their Own Words", which is a must read if you want to hear some quirky stories about Brian told by others.
There is the Shortin' Bread story where Brian has (I believe) Danny Hutton, Iggy Pop and maybe Alice Cooper singing SB at a piano during a party and after a while Iggy Pop realizes Brian isn't kidding and says, "I'm out of here, this guy is nuts!" or something like that. What a riot.
Another is the picture of Brian in his bathrobe (no shirt on underneath) at Keith Moon's B-day party in 1975....classic.
Finally, Brian asking his kids' school bus driver for a cigarette is sad but kinda funny too...
anyone have this photo?