I can find many instances of this expression, especially in descriptions of characters' lines in written dialog, but I can't find any mention to the expression itself. I understand that deference means polite submission and respect, so I take mock deference to mean that it's mocking someone by speaking with deference; like an employer calling an employee by boss.
Not being a native English speaker, I'm looking for a grounded meaning of this expression so I can be confident that I'm using it right.