From what I can piece together, Slim wrote this song about his time living in Detroit where an Armenian woman had taken him in and often cooked him Arabic food. The song, Yip Roc Heresy, is made up almost entirely of Arabic food names. "Yip roc" is actually "yabraq," stuffed grape leaves, and "heresy" is actually "heressah," a sweet semolina dessert.
So when you watch Sal and the gang singing along with Slim in the movie, you'll now know what the hell they are saying.
*Apparently, it was banned from at least one radio station.
** Lots of different spellings of this on-line.