Lyric discussion by tacobandit 

Cover art for Dead lyrics by They Might Be Giants

Here's my personal interpretation of the groceries lines.

Groceries: person. Shelved groceries: idle/bored/depressed person.

groceries are useful until their expiration date, that is if they are taken off the shelf.

'accidently' taken off the shelf means that there's no intent or purpose behind being useful.

coming back may mean reincarnation or rebirth... either from the dead (you can interpret this alongside easter religious philosophy or snapping out of a depressed funk...