Mel Brooks tells a joke:
Moishe and Mendel meet on the street. Mendel says, "I heard about the fire. It's terrible!"
Moishe says, "Shhhh! Thursday!"
This one is a "thinker." You have to figure out what he means by "Thursday."
I've noticed that in all Jewish humor, someone is being made a fool of, or refusing to be made a fool of. ("Taste. My. Soup.") In this case, the insurance company.
Why Thursday, though? "Tomorrow" is not funny, because it's not enough of a thinker. The joke hangs on the friction of the listener putting together what just happened.
"Friday" and "Monday" don't work, because they are special days of the week. They mean something, and that would be distracting.
But why not "Tuesday" or "Wednesday"? The joke would work, but wouldn't be as funny. "Thursday" is funny. Why?
Is it that the "Th" sound is funny? But it's not as funny as "k" or "f."
If I ever meet God, I'll be sure and ask Him.