the saying no to receiving the mail would have been ok, but be very wary of swearing, even in accidental "jest", to many it simply isn't funny and to many its offensive.
its very finbarr saunders and i expect mr cuck, mr fack, mr billocks, mr dock, mrs vegina, mrs finny etc etc think that "joke" gets even more hilarious every single time they hear it... the 5,000th time being the most funny
i am certainly not offended, but sometimes its just too obvious to be funny, and becomes tedious and actually makes the person making the joke seem a little sad - especially since they are doing it in office documents!
the giggles raised will more likely be polite 'responses' rather than humour, especially since its clear its been done deliberately rather than a genuine mistake
remember the fast show character??