Seeing as how you are gonna have to get yourself and your costume to the house party somehow, and are in Ottawa, this might be a useful read for you unless you have already. This guy got all that attention for a belt of empty casings and BDUs.
Now picture walking to your ride's car (or your car). Or walking up to the front door of the house party. Or what happens if the cops show up for noise complaints or something else? Food for thought, nothing more.