Late Night Fantasies at Work

Working the night shift can be lonely, but it sure does leave plenty of time for thinking. Tonight I was sitting in my office at 3 AM when I started picturing my boss, let's call him Jack, walking in with a mischievous grin on his face. Before I knew it, my hands were slipping down to adjust myself under the desk, imagining us diving into some naughty activities right there in the office. My imagination got so vivid that I was practically panting and sweating from just thinking about it all. Jack's mouth pressing against mine, his hand sneaking into my pants, finding me already wet and ready for him. This isn't really a confession of something I've done, yet, but it sure feels like one in the making. Is this normal to fantasize about your coworker so vividly? Any advice for dealing with these kinds of thoughts?