Enter the 2WebSurf viewer - it is completely free to use. This is not intended to be used to be a way to hide the web pages that you view, but it could be used for this. If you view tons of porn web pages and you want it to look like you really don't, then this is the perfect browser homepage for you.
2WebSurf can easily be configured to automatically cover the web page after a specified amount of inactive time. By default, this happens after 4 minutes (240 seconds) of inactivity.
The cover url can quickly be displayed by pressing the hotkey. By default, this is the "ESC" key. In order for the hotkey to function correctly, the web page must have the focus; to do this, simply click in any non-linked area of the web page you are viewing.
The hotkey feature may not work in all browsers. This does work in at least Firefox and Internet Explorer.
This feature helps to reduce your history items. Once you are viewing any site in the viewer, the browser history only creates a single item - that only leads to the viewer. Additionally, the title that is used for the page as well as for the history item is taken from your cover page, not from the page that you might be trying to hide.