How long have you been there? If you leave quickly enough, you can just decline to mention the job, if you like; you're not obligated to give anyone a complete

How long have you been there? If you leave quickly enough, you can just decline to mention the job, if you like; you're not obligated to give anyone a complete accounting of your work history, and nobody will care about a few months' gap between jobs. It's also likely not going to be as big a deal as you think to explain that "the position turned out to be a bad fit", so long as you can talk about why that was, in a neutral, professional way which demonstrates that you are a reasonable person who knows what a good fit would look like.