The 21-year-old star, who is a judge alongside the music mogul on 'The X Factor' USA, was shocked when she heard that Simon and Lauren Silverman were expecting a child together and she is angling to play a major role in the child's life.
Quizzed on whether she was surprised about the news on 'The Tonight Show with Jay Leno' yesterday (17.09.13), she laughed: ''Who wasn't?''
She then added: ''I don't know how it did, I just ... it's not my business to ask but it happened, basically though I did say if I'm not the not the Godmother I would be p***ed''
Leno then enquired: ''Would you like to be the godmother?''
To which Demi replied: ''Yeah!''
Demi was recently given a goat as a birthday present during a trip to Africa and she thinks an animal would be a great gift for Simon when he becomes a dad.
She said: ''I should give him a goat, yes.''
Demi has previously revealed fatherhood has melted Simon's cold heart making him less mean-spirited on 'The X Factor' judging panel this year.
She said: ''He's [mostly] the same, but maybe he's gotten a little nicer this year.''
He also slapped a jet-lagged Taylor Hawkins.
The acclaimed performer had just cancelled touring due to a battle with cancer.