The act of putting your dong in the toilet and transferring it to the bathtub filled with water.
When I was at home, I had to take a shit. After I was done shitting, I gad to rinse my dong in the water of the tub. Then was born a new batch of bathtub toilet water dong
This is most typically referred to as the toilet bowl water once a man's penis as poked itself into the murky depths. When a penis infiltrates the vile waters of the ceramic oval office, the water turns into Dong Water. Similar to bong water in the sense that once clean water is now tainted.
In other cultures, known as "Poop Dick"
I was pooping at the public walmart restrooms and felt my dick submerge into the icy cold waters of the unknown. I knew immediately that I birthed a new batch of DongWater. Unsafe and unsanitary, I immediately ran away.
Derived from "bong water", the water used in a bong (obviously); and "Dog Water", one of the phony advertisements on "The Ren and Stimpy Show."
After a long night of drinking Rolling Rocks and playing video games nonstop, the Angry Nintendo Nerd had to reach for the pause button -- he desperately needed to let off a couple quarts of "dongwater"...