The merc with a mouth has never been one to let the rules of civilized society slow him down. So, when Deadpool was briefly inducted into the X-Men, he decided to get an old uniform out of storage - Jean Grey's. Needless to say, this didn't go over well with anybody. Especially since her original Marvel Girl duds showed a lot of skin, and Deadpool's skin is... how do we say this politely... completely repulsive. He claimed it was to give him a strategic advantage over his enemies, but I think he was just in it for the lulz.