No Joke

Two college football players were taking an important final exam. If they failed, they would be on academic probation and not allowed to play in the big game the following week. The exam was fill-in-the-blank.
The last question read, "Old MacDonald had a ________."
Bubba was stumped. He had no idea what to answer. But he knew he needed to get this one right to be sure he passed. Making sure the professor wasn't watching, he tapped Tiny on the shoulder. "Pssst. Tiny. What's the answer to the last question?"
Tiny laughed. He looked around to make sure the professor hadn't noticed then he turned to Bubba. "Bubba, you're so stupid. Everyone knows Old MacDonald had a FARM."
"Oh yeah," said Bubba. "I remember now."
He picked up his No. 2 pencil and started to write the answer in the blank. He stopped. Tapping Tiny's shoulder again, he whispered, "Tiny, how do you spell farm?"
"You are really dumb, Bubba. That's so easy.
Farm is spelled E-I-E-I-O."