It's a way to check if someone read your entire profile, so you can filter out people who are just looking for a free place to stay. For example, you could hid

It's a way to check if someone read your entire profile, so you can filter out people who are just looking for a free place to stay. For example, you could hide the word "pineapple" two paragraphs in and ask that people mention it in their first message to you.