Undertaker used the mask in the wwf because Mabel( vicera) "broke" his face 1995. If i remember it right he took it of during the royal rumble' 96 title match with Bret Hart when diesel interfered.
Please for the love o god Cena Turn heel at summer slam. I like cena, but his face run is incredible stale. ... A heel turn for cena could shake up the entire Comapany. Maybe they could start doing some good stuff again.