Thankfully its quite a rare ad and the simple solution is to refresh to get another ad but its still annoying when you get it.

What it does is on the menus at the top of the screen if you highlight one of them to view the links to the other pages, the T-Mobile ad overlaps the site's text making it impossible to see or click on the drop down menu. Whereas with other ads, the drop down menu overlaps the ad so that you can see the menu.

I've had that same problem The jokes on you though T-Mobile I'm with AT&T... wait the joke still may be on me

I had a similar issue with a few adverts for BBC Radio One on Game Trailers, but the worst ads are the ones that activate as soon as your mouse rolls over it, and when you click the "close" button, your mouse is left on top of the ad, meaning that once you move the mouse again, it begins to play again. Grrr.