[We Jews are not only not allowed to conduct business on Shabbat, we are not even supposed to talk about it...]
Yosef and Gidon meet in the synagogue one Shabbat morning.
Yosef: Not to talk about it on Shabbat, but I'm selling my car.
Gidon: Not to talk about it on Shabbat, but how much are you asking for it?
Yosef: Not to talk about it on Shabbat, but $13,000.
Gidon: Not to talk about it on Shabbat, but I'll give you $12,000 for it.
Yosef: Not to talk about it on Shabbat, but let me think about it.
They meet again in the synagogue Shabbat afternoon.
Gidon: Not to talk about it on Shabbat, but did you think about my offer?
Yosef: Not to talk about it on Shabbat, but I already sold it.