Hide affiliate ID in a joomla URL

Here is my Joomla powered web site: [login to view URL] Top-right, you can see an advertisement (purple-white colors, about [login to view URL]). When you click on the image, the full link in the browser address bar is visible: [login to view URL] Instead, after clicking, I would like to see [login to view URL] only. The point: wizzair measures clicks, etc., so replacing the long url with the short one is not a solution, certainly. I would like to cloak everything after wizzair.com. You have to: - offer a solution, with explanation - implement it I prefer existing, free Joomla plugin, or .htaccess magic. etc. You will be given a temporary access to the site. Basically, it must be a quick configuration task for an expert, with explanation.