Nerd!

Apparently this is a very old joke, but it's new to me, and man does it tickle my nerdy bone.

Guy is visiting New England for the first time. Lands at Logan, gets in a cab, and starts asking the driver for recommendations for things to do. Some small talk ensues.

Finally, the tourist asks "Where can I get scrod around here?"

Answer: "I've been asked that many times, but never before in the pluperfect subjunctive."