Laugh a little
Issy rings the bell of a very wealthy person's house in Hampstead Garden Suburb and when the owner comes to the door, Issy greets him.
"Sholom Aleichem, Mr. Goldstein. I'm collecting for the Loads of Money Yeshivah, and I'm wondering if a nice wealthy Jewish person like yourself wouldn't want to make a little contribution."
"The name is Gold, not Goldstein, and I am not Jewish."
"Are you sure?" asks Issy.
"But", says Issy, "it says here that you're Jewish and my records are never wrong."
"I can assure you that I am certainly not Jewish", replies Mr Gold impatiently.
"Look sir, I know that my records are never wrong. You must be joking. Are you sure you aren't Jewish?" demands Issy.
"For the last time, I am not Jewish, my father is not Jewish, and my grandfather, alav hashalom, wasn't Jewish either!"