Q.E.D is one of those abbreviations whose meanings I always look up and always forget. Today, I discovered it has siblings. Q.E.D is arguably the most popular one because I don't know the others. The ones I discovered today were Q.E.I. which has been written about and Q.E.F which had not.
Q.E.F is a translation of the Greek words ὅπερ ἔδει ποιῆσαι used by Euclid to indicate the end of the justification of a construction. It means "which was to be done". Now, I frankly don't know what a construction is. I do not even want to look it up because it would be some highly technical, abstract mathematical stuff that I would have to study hard to understand. That is too much work.
There is a genre of American films that applies American mannerisms to everybody in history. Thus, one sees people from the stone age or medieval era or Russians having contemporary concerns. In that vein, I imagine Euclid would be saying Q.E.D or F. or I. dropping his reed pen (or chalk because that would be cooler) in a dropping the mic manner and then walking away feeling cool.