from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. Informal In concealment: "'You'd better lie doggo,' I advised her out of my own nervousness” ( John M. Myers).
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adv. quietly in concealment
Probably from dog.(American Heritage® Dictionary of the English Language, Fourth Edition)