Sorry im unsure about this, my sister has blacked out a couple of times during work, she is under an incredible amount of mental stress and suffers badly with depression, she has not done anything whilst passed out so i dont know if it is the same as you, i thought this was due to mental and physical exhaustion and she is also extreemly anemic so i think maybe these factors have something to do with her blackouts.
If its happening frequently i think you should visit your gp and get to the bottom of this.
I hope this has been even a little helpful to you.
Let me know how it goes.
Take care