"It's a party!" Deadpool said, immediately plunking down a party hat on her head at a jaunty angle, to match the one he was wearing (and most of the security guards, by this point, not wanting to risk the disapproval of the crazy man with the big swords). "Everyone around this place was so grumpy, so I'm doing my part to raise morale. Plus no one threw me a welcome party, so I figured I'd take care of it myself. Wouldn't want to embarrass whoever's in charge of throwing welcome parties, I'm sure sparky's just been tied up with work and wasn't able to run to the store to buy Welcome Deadpool streamers."