A Jewish doctor makes a great medical discovery for which the Queen has decided to grant him knighthood. At the ceremony, as she touches his shoulders with the sword, he is supposed to recite an ancient Celtic blessing.
However, for all his medical genius, the doctor cannot seem to memorize the required Celtic words. On the day of his investiture, the nervous doctor waits his turn as several others are being knighted before him. As he listens to one after another correctly recite the Celtic blessing, he grows more and more nervous.
Finally, when he kneels before the Queen of England and she taps his shoulders with the sword, the good doctor completely forgets the Celtic words, and substitutes the first foreign words that pop into his head: "Ma Nishtahnah Ha Lailah Ha Zeh."
The Queen, clearly confused, looked to the gathered crowd, and says, "Why is this Knight different from all the other Knights?"