Colon cramp. I have NO idea what it actually means but that's what the doctor diagnosed me with.
It started around 12:00, just slight pain in my lower belly. I slept for few hours and woke up, the pain was getting worse. I have a sensitive stomach, so regular painkillers would have only made it worse. By 18:00 it was hurting so bad that I couldn't stay still, I was pacing back and forth around the house. Then I sat in the toilet for few hours, puking and sh*tting my guts out, I puked so hard that I got a nosebleed. The pain was just getting worse, by 21:00 I felt like I was going to go mad.
By 22:00 my mother finally agreed to take me to the hospital(she thought it to be just extraordinary nasty heartburn). 30 min drive there, and 15 min waiting, I was literally writhing in pain. The nurse asked me bunch of stuff, I gave vague answers, "yes, "no", "painkillers plz". I'd liked to be more cooperating, but it just hurt so much that I was ready to start sharing the pain with others.
Then FINALLY the doctor took me in, poked my belly a little, said that my pee- and bloodtests hadn't shown anything fishy, so he suspected a colon cramp. Injected some sweet relief straing in my bum and sent me home, thus ending my 10 hours of pain.
The runner up is when an atheroma(http://en.wikipedia.org/wiki/Atheroma) was cut from my scalp, twice. Both times there was a nasty infection on it, so the anesthesia didn't kick in as much as I'd had liked to.