"if i don't see you again, have a nice life"

i'm not going to ask everyone I meet for an address and phone number... That holds especially true on the train, where more of them seem to want to talk to me. I'm always up for a good conversation, but I have too many friends as it is.
So, to avoid any awkward goodbyes, as we part, I offer some semblance of closure by telling them, "if i don't see you again, have a nice life."