X17 XCLUSIVE: It's A Pillow Boy!

Pete Wentz and Ashlee Simpson have been keeping awfully quiet when it comes to details about their forthcoming bundle of joy - but yesterday, they let one big tidbit slip!

We caught up with Pete and Ashlee three times yesterday, and every time brought a new twist to the story. First, we caught the couple in the parking garage of the Beverly Hills Medical Plaza, where they claimed ignorance about the sex of their baby. After that, the couple headed off to the California Pizza Kitchen for lunch - and upon their return, Pete pulled a pillow out of his trunk and started joking about how it was his baby!

Eventually, however, the laughter died down - at which point Pete confirmed that he and Ash would, in fact, be having a boy. Of course, by that point, we weren't sure whether to believe him or not - until our photogs caught Ashlee accidentally referring to the baby as "he"!

Sounds like a confirmation to us!