Britney Spears is thrilled about her Las Vegas residency and for the stability it will enable her to provide for her two sons, Sean Preston and Jayden James. However, her claim that she may bring her tykes onstage didn't sit well with their father, Kevin Federline ... and that's not good, because he shares joint custody of the boys.

When TMZ asked what he thinks about Spears performing in Vegas, Federline, unloading groceries into his car, kindly replied, "I think it's cool, man."

But the onetime backup dancer's tone changed when asked what he thinks of his eldest son with Spears, Sean Preston, appearing onstage. K-Fed sneered, "I mean, we'll see about that, won't we?" When pressed on whether he'd like Sean Preston (who the videographer irritatingly kept calling "Preston") onstage, Federline grinned, "I mean, yeah, if he was like, 25 years old."

Federline also revealed he wouldn't be watching his former wife's residency performances, chuckling, "Nah, that's not my thing. When I'm in Vegas, I'm at the craps tables."

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