A magical place that defies the laws of physics; the staff won't remember your visit, and no-one saw it happen
The phrase comes from a popular pizza eatery in Woking that may be cited as an alibi whenever you're accused of something that you definitely did, but don't want to admit.
I can't have had sex with my good friend's trafficked child prostitute because on the night in question I was in Woking Pizza Express.