Katie, the man doesn't even have a sense of humor!
From CNN.com (via Lisa):
The culprits were a fake reporter and camera crew working for a British comedy show.
The "reporter" held up to Cruise's face a bogus microphone that squirted water. An unamused Cruise told him, "I'm here giving you an interview and answering your questions and you do something really nasty. You're a jerk."
Police arrested the fake reporter and three members of his camera crew. They could be charged with assault.