By your own words you were called not because any ability of yours stood out, but because you did the right thing to suck up on the right day.
That makes it a good example of how little skill and ability mean in the interview process. That's broken; say the right thing or do the right thing and you're in.
"say the right thing or do the right thing and you're in".
Knowing what those are and how to do this is, by most measures, a good skill to have.
"you were called not because any ability of yours stood out, but because you did the right thing to suck up on the right day".
In that case, the birthday thing was a total fluke, and not really that big a deal, more a happy coincidence. But as I mentioned before, I wouldn't have had an interview in the first place without a baseline of skill/ability already demonstrated through other means (online portfolio, resume, phone screen process). The ability to make a positive memorable impression is, imo, an ability that did stand out.
Applying De Morgan's laws to fix how to determine if you're in or not then yields:
say the wrong thing AND do the wrong thing
I would also like to point out that an ability of your parent poster clearly stood out, that of making themselves memorable. Hiring is a multivariate problem, focusing on just one of those variables could be the most broken solution within the space.
That makes it a good example of how little skill and ability mean in the interview process. That's broken; say the right thing or do the right thing and you're in.