Variation of piss, most usually used in the north (particularly Scotland).
stop talking pish
what a bundle of pish.
A modification of twat
, (literaly, little twat) used as an insult, and is useful when an extra sylable is needed in an amusing poem or suchlike.
My heavens, isn't Mary and Jimmy's boy a twattock?
Yes, but what did you expect from those two?
Lacking the ability to speak
I wish you were dumb, then i wouldn't have to listen to you talking pish all day.