Currently

At the moment I am surfing the Internet from my sister's house while her two dogs stand guard at the door. They saw a man ride by on his bike a minute ago. He must have had a mean look in his eye or have been carrying a bazooka because the sight of him made them go crazy. I was tempted to release the hounds. Speaking of release the hounds, where did that phrase come from? And why is it in my vocabulary?