So what are you saying? People are not allowed to make a joke to a member of the opposite gender? It is not tznius to make a joke? To make someone else smile?
Well, now I know you are wrong! Because I have interacted with different respected Rabbonim and they actually said something in jest to me! Yes, they said something jokingly to me! And I never, in my wildest imagination thought that they were flirting with me! Imagine that! One Rav is actually almost 80 years old and he said something funny and I laughed.
I guess it is all in the way you interpret the situation.