1. (noun) One who pisses; a uriner.
2. (noun, British) A contemptible person.
3. (noun, Slang) A toilet, urinal, or any object in which one can piss in.
4. (verb) To be streaming with blood.
5. (noun) One who pisses too often or too regularly.
6. (down the pisser) Wasted; not put to good use.
You are such a pisser. (sense 1, 2 and 5)
Be right back, I need to use the pisser!
All that money I saved up is down the pisser thanks to you...