remember what to say only on the way out

[candidopereira]

Can someone tell me an idiomatic expression that is used when one only remembers what to say after needed?
Thank you.
I'm sorry for my bad English.

[MrPedantic]

Hello Candid, welcome to Using English!

I can only think of "staircase wit" (or, more usually, "esprit de l'escalier" or "esprit d'escalier"), which means the witty things you think of on the way home, when it's too late to say them.

All the best,

MrP

[candidopereira]

That's it! That's what I was looking for. I knew that was something in french.
Thank you.