If you go from the "My posts" tab directly to New question, the tag "myposts" will automatically appear in the Post Tags field. Therefore a large number of posts is tagged with "myposts", or "bookmarks" if you visit this page first. It's not a big deal, but just in case someone is wondering where these come from. As the number of tags per post and the tag length is limited, users might want to delete them from their posts.