My lowest round is 62 (-8) on a fairly easy golf course. I was 18 at the time, right before I started my college career. I still don't consider it my best round. That would be a 66(-6) at Alvamar Hills, in Lawrence, Kansas. I had two eagles, six birdies, and two three-putt bogies.
I don't play nearly as much as I use to, so the under par rounds are pretty rare now. I have more fun now helping my children learn this great game.