Slut-shaming
"Putting out" is seemingly expected of the girls, but they also get demonised for sleeping around.
Rizzo is the most sexually-charged Pink Lady, and is known for getting with plenty of men.
The character is demeaned for her sexuality, and is considered as "trashy and no good" by her neighbourhood.
Then, once Rizzo believes she is pregnant, her peers become even more ruthless with her and berate the Pink Lady for what she does behind closed doors.