Castor Oil is a disgusting vegetable oil that can successfully be used to bring on labor. I know it because I have done it! The birth story of my second daughter was somewhat crazy, and I kept meaning to write it up. But first, here's the recipe:
2 oz Castor Oil
2 Tbsp Almond Butter (the smooth kind, buy at Trader Joe's)
1 cup Apricot Juice
1/2 white wine, champagne or cava
Blend thoroughly. Enjoy quickly. Though the ingredients are sort of odd and you're hereby instructed to consume a moderate amount of alcohol while pregnant, I promise you this tastes a lot better than the usual recommendation of mixing the Castor Oil with OJ or even put it in a screwdriver. Again, I know because I have tried! You can expect this to work within 2-6 hours. My recommendation is to wake yourself up at about 4 am, after a night of a good dinner and decent sleep if you can manage. Drink the stuff and go back to bed. That way you might sleep through the nausea that sets in 1-2 hours later. Also, the sooner in the day your labor starts the better off you are.
BTW - here's the birth story that goes with this recipe....