In a another version of the same joke the cabbie replies: "Do you mean a whorehouse or the State? House?"
I have two questions about this joke: First, why is that subjunctive pluperfect? In other versions the driver calls it "pluperfect participle" or "third-person pluperfect indicative". I do not see any indication of any form of pluperfect in any of these.
Second, are there (were there) indeed English dialects where screwed would be pronounced as scrod?