h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

How come you always have to go pee when you take a dump but you don't always
have to take a dump when you go pee?

I don't know the answer, if you're a man (being a woman myself). For women, I assume it's because the muscles that control the output from the bladder relax at the same time as the muscles that control the output from the bowels. If this isn't the case, then I don't know.

That only answers half of your question. You don't always dump when you go for a pee because the bowels can't get rid of what isn't there. There always seems to be something in the bladder, even if only a small amount. The pelvic floor muscles (which control the bladder's output) seem to automatically relax when a woman goes to the loo, so whatever is in the bladder comes out. I guess this is closer to the truth than my first answer, which said the muscles relaxed at the same time.

Seeing as people are into resurrecting threads at the moment I thought I'd have a dip and see.

Surely this thread could have been so much more!

If you think of poo as being like lightening and wee being like thunder...

I'm not sure about this and it is possible to dump without peeing but very rare. As a vaguely intelligent guess, perhaps the sterility of urine goes some way to counteracting the harmful aspects of faeces?

Is this the case with other animals?