(Actually "Boo-Berry") A light blue, blueberry flavored breakfast cereal whose "character" looks suspiciously like "Casper the Friendly Ghost" wearing a little yellow hat. One of General Mills' three marshmallow "monster" cereals — the remaining two being "Franken*Berry" (a pink, strawberry flavored cereal personified by a Frankenstein's Monster-esqe cartoon character) and "Count Chocula" (a brown, chocolate flavored cereal personified by a Dracula-esqe cartoon character)

OR

One of three players in the General Mills breakfast cereals trinity that dare not speak its name.

The other two players being of course:

Like something out of a Michener tome, Boo Boo Berries are blue, hide an amusing berry taste—dare I say "berryrific"?— and are personified by a soul of the dead. This ghost, this hovering spirit rises above the bowl taunting us with what it cannot put to words.

We are left confused. Are we to eat this offering? Or rather, should we run as fast as our legs will carry us — far away — to where there are no spoons or bowls, just the blissful mutterings of times past.

I believe it was Benjamin Franklin who said:

"Three can keep a secret if two of them are dead.".
Indeed, this may speak volumes to some malignant secret that needs to buried — for while I am able to obtain Frankenberries and Count Chocula at my local Kienows, strangely, Boo Boo Berries no longer grace the shelf. It may also warn of things to come... Chocula, Frankenberry... watch your backs!

[cue lightning and thunder, send royalties check to Vincent Price]

Quoth the raven: "no comment"

[Update: Boo-Berry can be purchased from General Mills' web site]