Three little boys

Three little boys were sitting in the schoolyard and bragging about how great their fathers were. “My dad’s the fastest runner in the world,” said David. “He can fire an arrow, put the bow down and reach the target before the arrow!”
“That’s nothing,” said Kevin. “My dad’s so fast that he can fire a gun and reach the target before the bullet.”
“You guys don’t know what you’re talking about,” smirked Alan. “My dad works for the government. He’s so fast that he finishes work at 5pm and is home by 3:45!”