Proud new papa Brian Austin Green has a special lady he'd like to thank -- and it's not wife Megan Fox.

Instead, Green told Ryan Seacrest during a Tuesday chat with the deejay that he appreciates all Reese Witherspoon did to provide him and Fox with some privacy after they welcomed their son Noah Shannon September 27 -- even if it was totally unintentional on Witherspoon's part.

"We got really lucky. And I've been wanting to send Reese Witherspoon flowers for, like, a month and a half. 'Cause she actually gave birth, I think the day before us in Santa Monica," the 90210 alum, 39, explained. "We were lucky enough to go in at 2:30 in the morning to the hospital and nobody knew. We were there for two days . . . and we heard Reese was at her place and had a baby, and we got out of the hospital and nobody knew [about us]." (Witherspoon and husband Jim Toth welcomed son Tennessee September 27).

"We got home and thought, 'This is unbelievable,'" Green added. "Because we weren't expecting to get away with it. So we just figured we would go with it as long as we could."

Nearly two weeks later, Fox finally took to her Facebook page to break the news that her and Green's bundle of joy had arrived.

"We are humbled to have the opportunity to call ourselves the parents of this beautiful soul and I am forever grateful to God for allowing me to know this kind of boundless, immaculate love," Fox wrote. "Thanks to those of you who wish to send your positive energy and well wishes."

After discussing his wife's sweet message on the show, Green said he had one additional thing he'd like to add to it.

Joked the actor, "Reese, your ice cream cake is on the way."

This article originally appeared on Usmagazine.com: Brian Austin Green: I Want to Thank Reese Witherspoon for Helping Keep My Baby With Megan Fox a Secret