Best I've seen was one of my own... that was aiming at me.
Back in my early days of playing the game, I discovered how well Missile/Missile did against pirates. "Self," I thought to myself, "I should make heatseeker turrets for my station!" So I did. And then the pirates showed up. Thing is, these pirates were smart. They stayed close enough to trigger the turrets to fire, but stayed far enough away that all of the missiles went out about half way, then turned around and came right back at me.
Did I mention these were the bad old days when missile explosions penetrated through station walls?
So yeah, multiple deaths while I frantically scrambled for the build block. I finally get there, and in my newbie panic I think "I'll just remove the turret docks and that'll stop 'em!". Yeah no, now I had half a dozen heavy missile/missile turrets spewing heatseekers, and the twisting made them hit the station physically and propelled them out into space all around my station.
Before I had rogue turrets, now I had created my own freaking MINEFIELD!
Long story short, I finally had to beg on general chat for anybody with a ton of shielding to come blow my own turrets out of the sky.