what was the moment you realized you were leaving your youth behind and starting your evolution into a crotchety old man?

1976. I was sitting at the kitchen table with my gf's family, drinking shots of tequila with lime wedges, when her dad accused me of already acting like an old man.

The morning after my 30th birthday party, a teenage boy at the table next to us at brunch had giant headphones on and his face buried in a smartphone or iPod touch or something. When he snapped at his mom when she tried to get his attention and she meekly looked away - my reaction was "my parents would have smacked the shit out of me, and rightfully so."