I had some fun and games last summer while on a solo XC.
I was transiting through some Class D airspace enroute to a smallish airfield on the other side of the zone. My workload was quite low, I knew the route well and I pretty much had the destination in sight. So I was happily flying along through the zone, continuing a lookout, monitoring the instruments, the usual things, when I start to hear a buzzing noise. Initially I thought that a door or seal had come loose, or I had gained a wasp in the cockpit. I looked down to the floor to find the source, in doing so I also partially looked down out of my side window. When I looked down I found the source of the buzz, an aircraft was just about to climb into me from directly underneath. I promptly pulled and rolled over, making a climbing turn 90 degrees off track. I also quickly blurted out, "xx Radar Gxx taking avoiding action for traffic". Air Traffic were quite good with it actually, they cleared me to a higher altitude so as to avoid the traffic by a safe margin and informed me that he wasn't actually talking to them either.
I regained my original track and headed off to my destination. Had a quick bite to eat then pushed off home...where I collected my AS level results in the afternoon....a real fun day!
ASI