Description:

The term 'pissy' appeared in Common during the early period from unknown origins. English is the most likely origin, but there are many languages which have effectually this word with this meaning which would have reinforced the borrowing. Historically, the 's' has been long, leading to the standardized spelling having the final y to comply with Common phonotactics. 

'Pissy' is also used in slurs - because in its sense as a slur is often directed by the poor towards the rich, this probably explains why pissy is unusually vulgar and taboo, given that scatological vocabulary isn't normally terribly taboo in Commonised culture.

Noun: 

As a noun, pissy refers to urine. With an indefinite article, it can also have the sense of an instance of urination. Phrasally, the expression 'te wero y pissy' is a way of saying urinate. 

'Pissy' can also be used as a slur against a person. It has a sense like a person who has a high opinion of themselves who is wilfully useless and stupid.

Verb:

As a verb, 'pissy' is an intransitive pali verb meaning to urinate. The benefactive noxaj form can add a dative object urinated on or in. 

Modifier: 

The modifier form 'pissys' is a pejorative with a sense like useless and stood stupid yet arrogant.