Yes, I had one once, had a new firearm and wasnt familiar enough with the manual of arms of the particular model and ended up firing a round off into the ground...
It was a Taurus semiauto 45 (forget actual model #) with a "double strike" feature that had an extremely long trigger pull and this was the first time I had tried to shoot it. It didnt fire at first (I thought the trigger was broken or something, I pulled it so far past any other firearm I had ever shot and there was zero resistance to the pull) so I took/turned it off target but FAILED to remove my finger from the trigger, and in fact, continued pulling it..... scared the crap out of me when it went off.....
Yes, I WAS NEGLIGENT..... nothing wrong with the firearm, and it was not an accident...