The 53-year-old Cowell is expecting his first child with New York socialite Lauren Silverman, and Hudson—who is mom to 3-year-old David Jr.—is keenly ecstatic about the X Factor judge's upcoming journey into parenthood.
E! News caught up with the Grammy- and Oscar-winning star Wednesday at the 2013 Do Something Awards in Hollywood, where, we discovered, she was still reeling from the wonderful, if surprising, news about Cowell's growing family.
"You're the third person who's said that to me today, and it still has not sunk in," Hudson, 31, revealed when we asked her about Cowell.
"Congratulations to Simon—I'm sure he's going to be an amazing father," she gushed.
Still, Hudson couldn't resist the urge to take a dig at the famously testy, cantankerous and droll Cowell.
Talking to directly to the camera—and to Cowell—Hudson cracked: "Go easy, don't treat him like the American Idol kids. Be nice to him OK, Simon? Jeez!"
And she was far from finished roasting her pal.
"Imagine him as a dad?" Hudson added, before putting on a British accent: "Dahling, what are you crying for?"
Hudson immediately erupted into laughter. "I mean, what's that gonna be like? 'This baby doesn't have the It factor, the X factor!" she said, taking one last friendly swipe.
This will be the first child for Cowell. Lauren is currently in the process of divorcing real-estate mogul Andrew Silverman, who, reportedly, is a friend of Cowell's.
A source tells E! News that although the ex-couple have been going through "a messy split," Cowell "became a shoulder to cry on for her."