Because "hedonist" takes too long to say, one who believes in the philosophy of or practices hedonism, the idea that life is meant for pleasure, or that the pursuit of pleasure is of the highest calling in life. This could include drinking, drugs, sex, or for the moderates, having fun. Has the connotation that one throws caution and wisdom to the wind. Not to be confused with heathen.
Doing only things that pleased herself, she was labeled a hedon by the religious community.