who's (someone) when (he's/she's/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
Farlex Dictionary of Idioms.

who's—when—'s at home

a 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?’
See also: home, someone
Farlex Partner Idioms Dictionary

when he’s, it’s, etc. at home?

(British English, informal, humorous) used to emphasize a question about somebody/something: ‘Shirley Hills wants to meet you.’ ‘Who’s she when she’s at home?’
Farlex Partner Idioms Dictionary
See also:
  • when he's, it's, etc. at home?
  • who's someone when they're at home
  • What's (something) when it's at home?
  • cloth ears
  • good on (someone)
  • good on you
  • good on you!
  • chip
  • chips
  • not a sausage