Happy New Year and "Have fun"

We have a local Safeway store in the small Harbor Bay shopping center, about a mile from our house.  I'm in there about every day because I have a UPS box at the UPS store, which is right next door.  Anyway, there is a Safeway checker who is pretty laid back and cool, but what makes him special is that once he rings up your groceries and you pay him he always says "have fun" as you depart.  He says this to everyone, every day, without fail.  I got to thinking about it and decided that "have fun" is a great "parting shot."  Better than "have a nice day" or "later" or "ciao" or "see you soon" or "take care," etc.  Think about it.  How can you say anything better than "have fun" to some one you are parting from?  Isn't that about the best thing that can happen to a person -- to simply have fun?  So, I've begun to use "have fun" myself and am finding that it makes me feel happy and seems to make the other person happy too.  So I say, "have fun."