A joke thread from an alumni mailing list I'm on. Here's the two best:
A single cryptographer bring a date up to an apartment.
Date: Do you live here?
A: No, it's a one-time pad.
I also know a really great networking joke, but i'ts about UDP so I don't know if you'll get it.
And in the Usenet tradition, feel free to add your own appendages.
Maybe there's a problem with my delivery?