"What the f*ck? Are you for real?" Cyrus exclaimed after a fan called her an "*sshole" for leaving a group of young girls who wanted their picture taken with the singer.
Cyrus, 19, and her Aussie boyfriend Liam Hemsworth, 21, were approached by groupies as they boarded a helicopter in the beach resort town of Malpais, according to footage broadcast Tuesday by Channel 7 news station in Costa Rica.
The former Disney star let a few adoring youngsters take her photo but then said, "Gotta go," as her helicopter awaited.
One person from the group shouted the expletive as Cyrus walked away, prompting the star to mouth off.
Although she was visibly annoyed, Cyrus regained her composure and let fans continue taking photos before she took off.