It is where you mind fuck a friend/sibling or family member and in that mind-fuck you soon realized that you have also mind-fucked yourself.
Jake: He Dori! too bad we couldn't get in-n-out the other night because it was closed.
Dori: Actually there was some in-n-out wink wink
Jake: that was a great sexual innuendo Dori.
Jake: If only we had a sexual innuendo for that sexual innuendo....o wait, i just mind-fucked myself.
example of mind-fuck masturbation ^