Brian's answer of mock is quite apt, as evidenced by this usage note offered in NOAD:
imitate, ape, copy, impersonate, mimic, mock
A young girl might imitate her mother by answering the phone in exactly the same tone of voice, while a teenager who deliberately imitates the way her mother talks for the purpose of irritating her would more accurately be said to mimic her. Imitate implies following something as an example or model (he imitated the playing style of his music teacher), while mimic suggests imitating someone's mannerisms for fun or ridicule (they liked to mimic the teacher's southern drawl). To copy is to imitate or reproduce something as closely as possible (he copied the style of dress and speech used by the other gang members). When someone assumes another person's appearance or mannerisms, sometimes for the purpose of perpetrating a fraud, he or she is said to impersonate (arrested for impersonating a police officer; a comedian well known for impersonating political figures). Ape and mock both imply an unflattering imitation. Someone who mimics in a contemptuous way is said to ape (he entertained everyone in the office by aping the boss's phone conversations with his wife), while someone who imitates with the intention of belittling or irritating is said to mock
The word ape could also be used, although, to be frank, I rarely hear that word used in this context, with the exception of crossword puzzles, where "Imitate" is often the clue provided for the 3-letter word APE.