"Get you" was a British colloquialism. Sarah Jane Smith once said to Rose Tyler, "Get you, tiger!", when Rose seemed to feel that the term "assistant" didn't apply to her. It implied fake or sarcastic encouragement for Rose's position. (TV: School Reunion)
Behind the scenes Edit
American equivalents would be "look at you" or "check [this person] out". It's almost completely the opposite of the usual American meaning of "get you", which means "to genuinely understand a person well".