My best so far was thew first time I was allowed to solo outside of the pattern, it has a twist to it though. My Instructor told me to take off, and practice some turns, climbs, descents, etc. and to have fun. Well, my plan was to take off, and go fly around a nearby lake. This would involve some turns in both directions, and I assigned myself the altitude of 3000 ft. so that I would need to climb to after leaving the pattern. Well, it was a pretty warm day, so I had the window open when taxiing. I neglected to close it before starting my takeoff roll, no big deal right? of course not, I just waited until I had established a steady climb, and reached over and closed it. Apparently, in my haste I didn't get it latched properly because about ten minutes later, just as I was nearing the lake I heard sudden loud bang which scared the living poop out of me. The window had popped open . After gathering my composure, I closed it and continued my flight without event. Flying around that lake was pretty cool though, I hadn't known this, but apparently it is popular with water skiers. I could see the speedboats down below, and people fishing. This flight was the first time I had really felt at ease flying by myself (even with the window incident). It's what I call a pilot moment, where you say to yourself "I am an aviator!". I had rented a plane to go and fly around for a while, handled a small crisis, and brought the plane back safe and sound. I know it sounds cheesy, but that really is why it was my best flight to date.

P.S. Good topic, I've enjoyed reading everyone elses (more interesting) stories.