One day farmer Brown went to the barn to milk his prize cow. When he got to the barn he was shocked to find that the cows eyes were crossed! He thought, "This is a valuable cow, I can't have it walking around cross-eyed." So he called the Vet.
The vet came out and said he knew exactly what to do. He proceeded to take out a hose and stick it in the cow's butt. He then told the farmer to go around and watch the cow's eyes.
As the farmer was watching the vet took a deep breath and blew into the hose. To the farmer's amazement the cow's eyes went back to normal. The vet said that'll be $200. The farmer was a bit taken aback by the steep charge, but he was thankful that his cow was back to normal, so he paid the vet without complaint.
The next day, he went out to milk the cow as usual. To his great dismay he found that the cow's eyes were crossed again! He didn't feel like paying the vet again though, so he decided to treat the cow himself.
He began to do the same procedure to the cow exactly as he saw the vet do it the day before. However he could not see if it was having the same effect. So he called Billy-Bob the farm hand over and said, "I want you to watch the cow's eyes while I blow in this hose." Billy-Bob agreed and watched as farmer Brown did the deed. However, nothing happened. He reported to the farmer who tried it again. Still, no result.
Farmer Brown was stumped, so he told Billy-Bob to blow while he watched the eyes. As farmer Brown moved to the front, he saw Billy-Bob take out the hose and turned it around! Just before he put it to his lips, the farmer yelled, "What the hell are you doing?!"
Billy-Bob looked at him incredulously and said, "Are you kidding, you just had your mouth on that end!"