Diarrhea sucks because it feels like constipation with fiery asscrackers. There's nothing worse than taking a shit and having it just fall out your ass like the contents of a Big Gulps cup from 7/11 rapidly hitting the ground. To make matters worse you then try to wipe and to your horror you realize the shit went right through the paper and tainted your right hand. At that point you're sitting in a stinky hell hole with fire in your ass and shit on your hand.
In conclusion, diarrhea is much worse than constipation or Guild Wars