From the first-ever Itchy and Scratchy
cartoon, "Manhattan Madness
" (only without Scratchy) made in 1919.
It's a silent cartoon, accompanied on piano by the creator of Itchy, Chester J. Lampwick, and 'Itchy runs afoul of an Irishman' is one of the titles common to silent movies. Bart and Milhouse read them out, and Milhouse cries, "Watch out Itchy, he's Irish!". Itchy runs the Irishman through a roller-operated washing machine. The Irishman himself is a burly, bearded fellow in suspenders smoking a pipe.
Thanks to Servo5678 for the title of the short, I miss my Simpsons books!