About 4 years ago, I was at our flying site. I had brought two planes with me that operated on two different frequencies. Well, after flying the first one, I decided to fly the other. But I forgot to go to the impound shed and get the pin for the frequency that I flew the second plane on. So I am up in the air with my Advance 40 and all of a sudden it went absolutely ape sh*t. Turns out another flier had arrived and he flew on that same frequency and he was checking the control throws on his plane. Everyone at the field was ducking for cover. That Advance 40 did some manuevers that I could never imagine trying deliberately. At one point my plane was headed straight (and very low) right towards the pits at full throttle inverted!! I hollered out asking anyone if they were on Ch. 43. Fortunately, the other flier instantly turned his transmitter off. One wing tip just missed hitting the runway. Fortunately also, I stayed with the plane and regaining control, I managed to circle over the parking lot and then landed safely. Talk about a lesson learned. It was nothing short of miraculous that the plane didn't hit someone or something, much less land safely. God, I felt dumber than dirt for a while.