Have you ever had to do something āfor ballsā? You will probably think that the expression is talking about the testicles, but that is not entirely true. Doing something obligatory, without the possibility of going beyond it or out of necessity, is doing something for balls, but where does the expression āfor ballsā come from? Well, incredibly, it has nothing to do with the males of men.

This expression actually comes from Latin, but it didnāt say anything about ovum or ovi but rather it talked about opus est. Opus in Latin is necesidad and the evolution of the language made the word evolve to uebos, so that in old Spanish or if today there is still someone who claims to speak formal Spanish, they can use the word uebos referring to necessity.
Thus, āpor uebosā comes to mean āby necessityā. This is something that fits perfectly with the popular expression of obligation.
Now is it incorrect to say or write āfor eggsā? No, of course not. Although the evolution of the expression āfor uebosā has ended in changing the term uebos (need) for eggs (testicles), the meaning may be identical taking into account that it is usually a rather colloquial expression in which it could be said that doing something for eggs is doing something at risk. So itās do it yes or yes. I donāt risk my balls unless I have to.