To change the ending of a minor-key piece of music to a major key, adding a Picardy third (tierce de Picardie).
One can loosely refer to music that already has a Picardy third ending as "self-picardizing". Some examples include the "Little" Fugue in G Minor by J.S. Bach, "And I Love Her" by The Beatles, "Roundabout" by Yes, and N.I.B. by Black Sabbath.
"The last chord here is D minor. Do you really want to picardize it, using D major instead?"
"Yes, Number One, make it so."