Synagogue Twins (fried ham and eggs)

Jewish law does not permit eating pork. This fact found its way into restaurant slang, where “synagogue twins” became the slang for an order of fried ham and eggs. “‘Synagogue twins’ are fried ham and eggs” was cited in the syndicated newspaper column “New York Day by Day” by O. O. McIntyre on May 12, 1931.
 
“Hebrew enemies” (pork chops) is a related term.
 
Diner slang of this type became rare after 1960, and “synagogue twins” is mostly of historical interest today.
 
 
Newspapers.com
12 May 1931, Joplin (MO) Globe, “New York Day by Day” by O. O. McIntyre, pg. 4, col. 4:
New York, May 11.—The picturesque patter of the cheap cafes has spread to the glorified soda fountains. Among the Bowery many waiters call out their orders through the porthole to the kitchen. The jargon varies in different sections of the country.
 
On the Bowery “One in the dark” is coffee without cream. “Dude a Java” is coffee with milk. “Adam and Eve on a raft” is poached eggs on toast. “Five minute vest spotters” are eggs boiled five minutes. “Synagogue twins” are fried ham and eggs.