He calls it his P.S. de resistance.
Yesterday, my dad was talking to a colleague on the phone, and I heard him say "I can't find the footnote, it should say 'edited by [another colleague's name]'". So I got a marker, wrote the information on my foot, went up to him and said "I found the footnote" and showed him my foot. I got a thumbs up and a grin. Success.