What was so funny about a bungled divorce?

Austin Cavanaugh came all the way to San Francisco to tell Clea a joke. Clea Bannister--good old Clea--had unknowingly been Mrs. Austin Cavanaugh for the past seven, years. She wasn't amused. She'd always loved Austin. She still loved Austin. But she wasn't fool enough to tell him. If he ever knew, he'd split his sides laughing.

Clea maintained her calm while Austin amused himself by poking his nose into her business affairs and checking out her fiance. But when Austin announced that he liked being married and intended to stay that way, he carried the joke too far.