who's someone when they're at home
who's (someone) when (he's/she's/they're) at home
humorous Who is that person? Primarily heard in UK. Robert De Niro? Who's he when he's at home? I've never heard of that actress before, who's she when she's at home?
See also: home
who's—when—'s at homea humorously emphatic way of asking about someone's identity. British
1991 Joseph O'Connor Mothers Were All the Same The old lady said to tell that to Yuri Gagarin , but the hostess just giggled and said, ‘Who's he when he's at home?’