Who's (someone) when (he's/she's/they're) at home question
Used to ask who that person is
I don't know him. Who’s he when he’s at home?
Used to ask how someone behaves in the privacy of their own home
Celebrities always look gorgeous in front of cameras, but who are they when they are at home?
people often do irrational or foolish things when they are in love.
I and my boyfriend have decided to get married in the summer. I don't think that's wise, since we won't have enough money saved by then to set up house. But then, one cannot love and be wise.