Got this one from TvTropes...
An antisemitic priest was in charge of a town, and challenged the Jews of the town to a sign language debate with him, with a catch: if the person they pick to debate loses, all the Jews must leave. No one volunteers for the debate except a poor fool. At the debate, the priest draws a big circle in the air. The fool stamps on the ground. The priest holds up three fingers. The fool shakes his head and holds up one. The priest takes out bread and wine. The fool begins to eat an apple. The priest then declares that the fool had won the debate. The priest's explanation: "The circle meant that God was everywhere in the world. The stamp on the ground meant God was not in Hell. The three fingers represented the Trinity. Holding up one finger meant that God was one and indivisible. The bread and wine represented the blood and flesh of Jesus, but when he reminded me of the original sin, I knew he had won." The fool's explanation, on the other hand: "The priest pointed far away, meaning that all the Jews must leave. I stamped on the ground, to say that we're staying right here. The three fingers meant that we had three days to get out. The one finger meant that not one of us was leaving. Then, I guess he gave up, since he took out his lunch, so I took out mine."
(I don't think it's antisemitic, given that it's a traditional Jewish joke)
