A Mule Named Theo

I had a smart mule named Theo,
Would stammer and balk and bray;
And then Theo whirled to face me,
For Theo had this to say:
"If you need me at Boston Market
To pull this wagon today,
Theo wants apples and carrots,
Plus me usual oats 'n hay;
And when we're at Boston Market,
Load this wagon just as I say,
For if you dare to oppose me,
You pull it the rest of the way."