Noun
pish-tush (uncountable)
Alternative form of pishtush
Williams (2010), p. 267 and Pish-Tush; A character in the Bab Ballad "King Borriah Bungalee Boo" (1866) is the haughty "Pish-Tush-Pooh-Bah", which is split into two in The Mikado – the terms pish, tush, pooh, and bah are all expressions of contempt. Source: Internet
However, some vocal scores still include Pish-Tush in this number in his reduced role. Source: Internet