I love these jokes, they are quite useful. The reader can understand the last line if he uses his imagination - and distorts his beautiful standard English pronunciation. (So if you don't understand what the whole thing is about just read this joke aloud)
Here are a few such jokes based on homophonoids - words that sound alike but one of which is incorrectly spelt.
My favourite:
"Knock, knock."
"Who's there?'
"Oscar."
"Oscar who?"
"Oscar a stupid question and you get a stupid answer"
and this one:
"Knock, knock."
"Who's there?'
"Cows Go."
"Cows Go who?"
"Cows go moo, not who"