What have you never done in your life for which you don't have a really good explanation as to why? I'm speaking of the simpler pleasures, not necessarily something like you haven't yet climbed Mt. Everest.
For example, I've never had a massage. I've had some feeble mini-massages from my wife, but she is no good at it. So I have no idea what it really feels like to have a massage from a physical therapist or trained masseur.
I've also never driven, or even ridden, in a Corvette or Porsche. I've liked both cars since I was a kid, I have books on both, and even have a wheel emblem from a Porsche in my office that I purchased 15 years ago as my "first part" toward getting a whole one.