I'm more saying that having your work password be a naughty fantasy involving your coworker is just plain creepy. I've never heard of this. I mean, even having a naughty fantasy involving your partner as your work password is creepy. How can anyone think this is totally normal and appropriate behavior? I know my wife would find it real weird if that was my password.
If you do that, and are starting to feel like other people find you creepy or are suggesting you might be, and you're confused why they think that.. I just don't know what to say. If you were under the impression having such a password is common, I'm afraid you were mistaken.
But, like I said, I'm giving people an opening here.. maybe I'm the one that's mistaken, and naughty sexual fantasies with coworkers as work passwords is a very common and normal choice of password. Presented with such evidence, I'd reconsider.