I believe that this one is pulled totally from my own fat old lady brain.

At some point in my misspent youth, I started saying:

“And my ass chews crackers too.”

The general meaning of this is akin to “Pull the other one, it’s got bells on it.”  Or simply, “Yeah.  Right.”

I said this once to a legal secretary and she said, “WHAT?” 

I repeated the phrase to her slower and she said, “Oh.  That makes a lot more sense.  I thought you said ‘Cracker stew’.” 

Of course, I immediately fell in love with that wonderful abbreviation. 

I seldom use the abbreviated version though because my experience is that most people immediately understand “And my ass chews crackers too” but are baffled by “Cracker stew” – even with an explanation. So take your choice.  They are both satisfying and useful phrases.