How to bring on labor

My friend is due in 4days and she's trying to get her contractions up and going cause she doesn't want to go post her due date. Is there any home remedies that can bring on labor that actually worked for you or someone you know? I'd give her some advice, but everything happened naturally for me water broke at home 3 days before my due date and it was my first child i was 8cm when I got to the hospital so everything happened very quickly for me