If you ever get any mail from the TV talent show queen Sharon Osbourne, think very carefully before opening it, warns Martin Wainwright

Shit happens, as the increasingly widespread American expression has it. But if you aggravate Sharon Osbourne, it may happen in a particularly targeted and personal way.

The wacky queen of TV talent contests reveals in the Guardian's Weekend magazine tomorrow that she takes an unusually intimate revenge on critics who rile her - especially if they attack her and Ozzy's family.

Offenders can expect a beautiful box from the New York jeweller Tiffany's shortly afterwards. Inside, rather than diamonds, there is something only Mrs Osbourne can produce. Fighting giggles, she says: "I must have a thing, not about shitting but about sending it to people. I've done it for an awfully long time. I suppose I find it funny."

Mrs Osbourne admits being something of a revenge specialist, a trait she may have inherited from her father, Don Arden, a music impresario and self-styled gangster who reacted to bad news by threatening to kill whichever of his associates or relatives he considered responsible.

The scatological variation on the theme, however, is Mrs Osbourne's own. She describes in a new book how she adulterated Ozzy's cannabis with it to try to break his habit, and then added it to her father's most precious ornament when he stole from her. She tells the Guardian: "I mean, I don't just do it to anybody. They have to have done something really bad."

No Tiffany boxes have left the Osbourne mansion for a while now. But any harsh critics of the new book might be advised to examine their mail carefully before opening it. Sharon says: "The last turd? Three ... No, four years ago: when the first review came out of The Osbournes. And it was from a newspaper in America, a very legit one, not the American version of the Mirror or the Sun.

"The journalist said something about my kids being fat, and how unappealing that was. And I thought any journalist worth their salt would never write that about children in the society that we live in today."

On that occasion, Mrs Osbourne recalls, she added a personal note. "I said, 'I heard you've got an eating disorder. Eat this.' "

· Read Emma Brockes' extraordinary interview with Sharon Osbourne in full in tomorrow's Weekend magazine.