Weird old trick that doctors don't want you to know about - sleep every night with a pickled egg in your pants or at ball-height if you sleep nude.
The repugnant smell of vinegar will train your sperm over time to avoid eggs and swim in the opposite direction. Thus creating a natural contraceptive.
Listen here fucko, this is MY thread, I don't appreciate you coming and spoiling tip #5 weeks ahead of schedule.