The Mask star reveals she will be paying the new mum a visit this weekend (26-27Apr14) to introduce herself to Barrymore's second daughter, Frankie, who was born on Tuesday (22Apr14).
She tells U.S. talk show host Jimmy Fallon, "We have a baby girl! I'm very excited. I'm gonna go home this weekend, I'm gonna meet her right away. Little Frankie! So cute! I can't wait. I feel like I know her already!"
But cheeky Diaz admits she is planning to play a joke on the tot if Frankie falls asleep in her presence - just like she did to Fallon's baby girl Winnie at a party last year (13), when she stuck the then-six-week-old's hand into warm water as she slept, prompting her to urinate in her diaper.
The actress exclaimed, "She (Frankie) is gonna get initiated!", before defending her prank on baby Winnie, stating, "She fell asleep first, that's what happens when you fall asleep at a party!"
Fallon is good friends with both Diaz and Barrymore - his wife Nancy Juvonen is Barrymore's producing partner.