Any bottle that contains urine.Preferably with a lid, for multiple storage and disposal options.
Can be abbreviated as PB.
When someone is to drunk to make it to the bathroom they may use an empty bottle next to the bed to piss in.
When we were stuck in traffic Joe had to piss in his empty water bottle or he would have pissed himself.
Most pissbottles are clearly identifyable and cannot be mistaken for anything else.