Bill Pitts was kind enough to share with me the secret to the "Cockroach Pass".
Several old pros realized that the "pass" was more easily concealed from a small group than on stage, so for large groups they used the Cockroach Pass. When the selected card is returned to the deck you simply get in position to do the pass, then pretend to notice something on the floor. Stomp the floor violently as you make a funny comment on the number of roaches occupying your venue. As you stomp, perform the pass.
Believe it or not, I've seen Bill get away with this. Hilarious, AND I have no doubt this would work for a deck switch as well.
PS, I wouldn't use this in restaurant work.
You could get an offstage assistant to make the lights go off and when they do that say "uhhh, Max? Is everything OK back there? We seem to have lost lighting." if your doing it oon a stage, but if not just have someone release 1-2 real cockaroaches like chasegoforth said.