Looney Toons voice actor Bob Bergen explains the logic underlying Porky Pig's stutter, which is surprisingly regular.
The clip comes from the documentary I Know That Voice, produced by John Di Maggio, the voice of Futurama's Bender. Mel Blanc, the original voice of Porky, never explicitly set out these rules, but Bergen's reverse-engineering of them shows that Blanc had intuitively set out a highly systematic way of approaching Porky's stutter.