I had this experience a couple of years ago when I went to visit my sister in Richmond and saw the Arctic Monkeys. Truth be told, I was on a college campus, so it’s understandable that I (30 at the time) was a major age outlier in the crowd, but it was really jarring. I remember realizing fairly quickly that I was a solid 10+ years older than everyone, and so from then on it was just a blitz towards drunkenness to forget that fact. I don’t mean to brag, but… Mission accomplished.
For future reference: When you’re going to go to a metal concert while your pregnant wife stays at home and catches up on some work all night, just go ahead and leave a note on the counter. It’s not worth the fear of God that it will instill of you for the rest of your days.