The policeman joke here is from an old routine I read about in Vaudeville: From the Honky-tonks to the Palace by Joe Laurie Jr. Great book if you're interested in the history of vaudeville.

Ben: I'm looking through an old vaudeville book for some jokes.
Ben: Mr. Cohen, what are you running for?
I'm trying to keep two fellows from fighting.
Who are the fellows?
An Irishman and me.
Lewis: find one that is less racist
Ben: I'll try.
Lewis: ps: that exchange is my comments for today, including this line.