Since frankly.pitas uses Javascript, you could also leave that page, turn off Javascript, return to that page which will now stop sending those popups, use the search engine to leave it (type something random), and turn Javascript on again. All of this, IF you can access the menu. If you do not see it, try pressing alt.
To turn off Javascript, you generally go to settings/menu/etc., and this link explains how to turn it on/off on mutliple web browsers. http://www.alanwood.net/demos/enabling-javascript.html#safari
Sorry, I really can't type all of that out when a link can do it all for me.
Also, if you have the problem on an iphone, it could be much easier. Go to settings, safari, and scrolling down, you will see an off'on for Javascript. There are also other ways in that same Safari tab to fix the problem, using ideas others posted: you could clear cookies/history or turn private browsing on/off-- except this will close the pages you had open, which may not be preferable if you had something important up-- all of which can be seen scrolling down.
But I found the Javascript idea easier, personally.
Good Luck!