Essentially it’s the
polar opposite to phrases that use the word “Piss” to imply something is easy such as “
Piece of piss”, so Dog Piss would be used to say that something is hard or difficult. It’s related to the phrase “Dog Shit” in the sense of conveying
negativity.
Person 1: Yo, have you completed the Algebra and
Pythagoras homework yet?
Person 2: No, it’s utter
dog piss. I can’t seem to
work it out at all...
(maybe I should get off of UrbanDictionary.com and revise more instead of procrastinating.)