"They have this thing in French, l'esprit d'escalier. The spirit of the stairway. I don't think we have a word for it in English. It means, well, the clever things to say that you only think to yourself when you're on the way out. All the cool stuff you wished at the time. So I'm walking down the stairs, thinking..." -from Neil Gaiman's Death: The Time of Your Life
Honestly though, who else has ever thought they were the only one who thought up all the right words too late?