Say each letter that's capitalized, and say the words as you normally would. It's supposed to sound like a "conversation" between 2 southern people about ducks. I know, really dumb, but I remember hearing that in like, 6th grade and thinking it was the funniest thing.
Here's what it's supposed to sound like:

"'Em (them) are ducks."
"'Ay (they) are not."
"'Es (Yes) 'Ay (they) are.
See 'em (them) wings?"
" 'El (Well) I be!!
'Em (them) ARE ducks!"