I know most of you pee in the water while having fun, swimming in the river... If you're nasty enough, you would pee upstream so that the people downstream will all have a taste of your urine... Damn, you're disgusting! However, dont ever ever pee in the Amazon River (if you have the chance to go there)... Why? Because of this little fella...

Candiru, also known as the toothpick fish, is pretty nasty... Candiru swims into a larger fish and eat it from the inside... It enters the larger fish's body by going through it's gills and then resides in the body while eating its flesh... and the umbrella shaped body makes Candiru impossible to be removed... So, never pee in the Amazon River because it is feared that the opening of the urethra when you urinate will give the candiru an opening to enter your body... Once it enters your private parts, one of the ways to remove it is surgery... 

Urghh... and that would be extremely painful... If you think that the most wicked fish of the Amazon is the piranha, think again... At least the piranha will just finish you off... The candiru will torment you alive...