Show them a movie, rather than a TV show. it's a relatively small nugget, and it's almost like a spoken sentence, concise and complete, and first-time viewers will be familiar with the format. Showcase it in comfortable surroundings. Make the first-time viewer associate it, and your presentation, with pleasant things, like cake, cookies and sex. That way, when they think of anime, they'll think of cake, cookies and sex along with it. Choose a genre they like. If you don't want to find out, make an effort to scry their 10 most favoritestest movies, and pick one based on that. But above all, don't shit in the kitchen.