It is a sexual move, where the male is performing doggie style on his partner, and while her (or is guess his) face is burried into the ground, he forms his hands in upside down "A-Okay" gesture with his fingers, and wraps them around his eyes- forming a makeshift mask. The partner is not to know that this act is occuring at the time. As soon as he cums, he is to immediately pick up his cell phone (while the partner is still present) and call a friend and state "THE MASKED AVENGER HAS STRUCK AGAIN" and hang up immediately.
Guy: Did you get a message about a certain Masked Avenger last night?
Friend: Dude, you have deep-rooted issues.