One time someone on my team got sniped in Nimbus Ruins Zone, and I actually accidentally caught him with Tails over a death pit. Though I wouldn't really call that an 'owned moment'.
Another time, I was playing D00D64's Mario Kart pack at Peaches castle with 6 players. I was last the whole race but got a star and hit about 4 of the other racers and made it to 2nd place (because of the imbalanced star-time). Then at the part where you jump of the big red mushroom to the finish line, I threw a bomb right before the ramp. And a few meters before the guy in front of me finished, the bomb magically fell out of the sky at a quick and unavoidable speed and blew him up; and of course I luckily won. Both of our initial reactions were, "WTF!?!?", but I was literally laughing to death on my side.
Another time I was playing with Blitz-T in D00D's pack again at Sand Ruins. Blitz-T and me were the only ones racing, while Kyllian1212 was commentating (with spelling errors all over the place :P). It was pretty boring and one-sided the whole time until I got a redshell and threw it through the long hallway with the abilities. It ended up hitting him about 7 seconds later, and I got front row seats to it from the fly path (Not to mention it helped me win). What was even more hilarious is that one of the walls that he broke for the power path respawned on him for a second while he was down.
And one last time in Sand Ruins (Riders Mode, vanilla SRB2Riders), we were playing with a bunch of players, about 9 IIRC. 5 people were on my trail at the end section with the auto-guided sequence that takes you above ground again. I hit an invincibility monitor and unwillingly attacked 4 of the 5 people racing head-to-head behind me at the turn around.