Mr. Dog, is there something I should know?

Mr. Dog is one of those people who is always warm. I joke that he wasn't born, he was chipped free from a block of ice and thawed. So it was no big surprise when he came in after shoveling snow and announced he was burning up. He sat down and took off his shirt to cool off.
Big Dog took the chair next to him. He looked at his dad's chest and asked, "Why are you covered with this?" tugging at a bit of his chest hair.
Mr. Dog explained that it just grew there, and that when Big Dog got bigger, he'd probably have his own.
"But what is it?" Big Dog asked, still tugging.
Little Dog, who was standing nearby offered his thoughts, "Dog hair!"
Wow, I had no idea.