The 'accident' a responder mentioned is caused by pressing down the power key (right side) and the volume-down key (left side) at the same time. This is easy to do when grasping the Galaxy Nexus with the right hand and pressing the power key with the thumb, not realizing that the index finger is pressing the volume key on the other side.
Are you referring to a response in another discussion on this community? If so, why didn't you reply in that discussion. Otherwise this post makes no sense.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
My apologies...a newbie mistake. The discussion thread in question is "Nexus Update" by medic69405, and the responder is Jax_Omen. I failed to add that the same combination key pressing (power-on/off + volume-down) that generates the dev-screen with the little green guy also generates a screen capture pic (filed in the sdcard0 directory) when the phone is fully powered.