Well done ! That’s the right answer.
‘And pigs might fly !’ is something you say when you think there is no chance at all of something happening.
French translation
Quand les poules auront des dents.
...................................................
Examples in context
‘How will the referendum have changed the coalition ? So after Cabinet bust-ups and public spats, can the coalition simply stage a group hug in the wake of the AV referendum, and return to business as usual ? Pigs might fly.’
BBC News, UK politics, 04 May. 2011
............
‘Philip Hensher : Battersea Power Station - The white elephant saved ? Pigs might fly … I see Battersea Power Station every day, and, even in its dilapidated state, it never fails to raise the spirits.’
The Independent, 08 Jun. 2012
...................................................
Everyday usage
I’ll pay you back on Friday, I promise. Yeah, and pigs might fly !