When I was pregnant, a ton of random people used to come up to me at the grocery store, movie theater, walmart - everywhere - giving me unsolicited advice. It was like I was wearing a sign. A few times it was a birth horror story of someone they knew, sometimes it was asking me if I was having twins, and once it was a waitress telling me to not drink decaf coffee because it would give my unborn child pink eye. (I wish I were joking).
All of my friends seem to have experienced this bizarre phenomenon as well, so I guess there must be some sort of Protect The Children collective group thing going on.
In any case, I find this strange phenomenon happening again as a new professor. I get unsolicited advice early and often from others. It's often pre-packaged tidbits, like, "Teaching is like a gas - it consumes all space available". Sometimes it's strange things, like the more senior assistant professor who put a hand on my arm, looks me in the eye and says, "It gets better." (like I was grieving the death of a loved one).
I know this is all well intentioned, but sometimes when I get unsolicited professorial advice I desperately want to say back, "YES. I AM HAVING TWINS.", just to see the look on their face.