After explaining that I've applied to grad schools:
Response 1): "Ohhhhh....*grimace face*"
Response 2): "But you can stay at your job if things don't go well, right?" (e.g. yeah, this may not work out for you. Don't quit your day-job. Literally.)
Response 3): "[insert obscure, most likely deceased relative] was a professor! It's in the family!!!!"
Response 4): "You'll make a great teacher. Wait...can you do things other than teaching with a Ph.D.?"
Response 5): "Where are you going to go? Oh you have to wait on an acceptance? Well, have you heard any news yet? No? So when will you know? That long of a wait?! You must be sooo anxious." (very unhelpful)
Response 6): "Wow, it sounds really expensive to apply. I can chip-in $20....if you really need it. Just try to save your money."