If you are asking about the actor, he has professed to be Jewish. But the character in the series never makes any direct relation that he's from the Jewish faith.
I have never found him funny and I seriously hate fake laughters in the show.
I believe you are referring to an episode of "Curb Your Enthusiasm with Larry David, the co-creater of Seinfield
Larry David opened in Little Rock. Actually it was Larry Miller who opened for Jerry in Little Rock.
NEWMAN !
In the episode when Jerry had flees Elaine lost her article for work and had been raiding Jerry's apartment as it was being fumigated for flees. She emerged with a few "Chunky" wrappers and Jerry then knew it was NEWMAN ! Then proceeds to say " I KNOW THE CHUNKY THAT LEFT THESE CHUNKY'S.....NEWMAN !!!"
I believe it was Moosehead Beer he did radio spots for.
Actually, Seinfeld did radio ads for Grizzly Beer during the mid-1980s. The ads began with Seinfeld saying "Grizzly is a bear, no Grizzly is a beer..." I heard them on the New York City all-sports radio station each morning when my radio alarm clock woke me.
"Monk's Restaurant"
The diner in question is in reality called Tom's Restaurant, and it is located at 112th and Broadway on Manhattan's Upper West Side.
The Late LLOYD BRIDGES played IZZY MANDELBAUM, Jerry's personal trainer on Seinfeld (save some oodles for me)
Jerry Seinfeld's character dated a total of 66 different woman throughout the show, many only lasting one episode.
For a complete list of all 66 of Jerry's dates, along with summary of the character, and the episode(s) they appeared in, Google search for 'Kramers Apartment seinfeld's girlfriends'.
(KramersApartment is a fan site dedicated to everything Seinfeld)
Numerous now famous actresses played his girlfriend, including Courtney Cox, Anna Gunn, Lori Loughlin, Teri Hatcher, etc.
He sold raincoats for 35 years. The executive he called it.
Celebrity impersonation is not illegal unless it is intended to cause harm. Same goes with anyone else you impersonate.