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"Holy crackers! Mrs F is pregnant," the Scottish funnyman wrote this afternoon. "How did that happen? ...oh yeah I know how. Another Ferguson arrives in 2011. The world trembles."
The thrice-married Ferguson, 48, also has a 9-year-old son, Milo, from his second marriage.
He and Megan, an art dealer, tied the knot Dec. 21, 2008, in a private ceremony on the family's farm in Vermont.
"The wedding took place in Vermont, where they have legalized gay civil unions—and I married a woman," Ferguson quipped in his postmatrimonial monologue.