I am not a native, but I would make two guesses as to why it sounds funny:
1) It could be because expresses that the speaker finds that person endearing. Since is a position that holds superiority, the use of now becomes condescending and rude.
2) The other reason I can think of, is that in japanese the combination of and that I have seen are applied to the elderly while still holding the endearing quality such as and . Substituting in place could show that their still maintains a characteristic of being amicable between the person and speaker regardless of the title.