Osbourne: I'm going to be grandma 'from hell'

"I am going to spoil this baby so bad," Sharon Osbourne said.

STORY HIGHLIGHTS

• Sharon Osbourne's son Jack and his fiancée Lisa Stelly are expecting a baby in April


• "I'm getting more and more excited," Osbourne told People


• "I am going to be the grandmother from hell," she said

() -- Sharon Osbourne has never been known to hold back -- and she certainly won't start when her first grandchild arrives later this year.

With son Jack and his fiancée Lisa Stelly , the giddy grandmother-to-be is already counting down the days.

"It just gets better and better, the thought of it, as we're getting ," Osbourne, 59, told PEOPLE at Guitar World's Rock & Roll Roast in Anaheim, California on Thursday. "I'm getting more and more excited."

Holding off on buying for baby until the big debut -- "I'm very superstitious," she reveals -- Osbourne isn't shy about sharing her future intentions!

"I am going to be the grandmother from hell because I am so bad," she says. "My son and Lisa are going to be like, 'Get her out of here!'"

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