Bisacodyl
"I realized it's been about 6 days since my last bowel motion.  I took this around 1:00 pm today so I wouldn't have to lose any sleep or deal with it tomorrow at work.  I took it with a swig of water and about 45 minutes later started reading these reviews.  Immediately, I started drinking water and got about 40 ounces down within an hour or so.  I started getting very gassy with very mild cramps around 4:00.  Between 5 and 6pm I passed some soft stool a few times, but knew it wasn't the end based on how long I had went without a bowel motion.  I had a bowl of cereal around 8:00 and by 8:30 I was passing pretty frequently.  I only had extremely mild cramps and a couple hot flashes.  Be sure to drink your water."