The greasier, the better.
In Grease, innocent Sandy breaks up with John Travolta after he tries to pressure her into sex. For some reason, she immediately regrets this rash decision and sets about remaking herself in the image of the slutty women he seems to prefer. The change includes taking up smoking, changing her mannerisms and even getting rid of her accent.
Is Sandy in love or the witness protection program?
It's not just women who are encouraged to erase their personalities, though. In American Pie, Chris Klein can't lose his virginity until he totally transforms himself from a douchey jock into a douche bag who wears sweaters. And of course, in Grease, John Travolta can't make his car fly until he undergoes a personality wipe that takes him from greaser to ... greaser in a sweater?