"Wowser" is an Australian and New Zealand[1] term that refers to someone who seeks to deprive others of allegedly immoral and sinful behaviour, such as drinking, smoking and gambling.
The term originated in Australia, at first carrying a similar meaning to "lout" (an annoying or disruptive person, or even a prostitute).
Historian Stuart Macintyre argues: the achievements of the wowsers were impressive; they passed laws that restricted obscenity and juvenile smoking, raised the age of consent, limited gambling, closed down many pubs, and in 1915–16 established a 6 pm closing hour for pubs, which lasted for decades.
In The Motor magazine w/e 10 April 1940, the word was discussed, and the author of the "Contact" column was still bemused until he received a card from a gentleman in Bristol who said "Broadly speaking, 'wowsers' are pious hypocrites, those who dislike seeing others enjoy themselves, usually in evidence amongst the elder members of a community."
However it appears several times in the works of H. L. Mencken: In Ocean's Thirteen, Basher (Don Cheadle) says to Linus (Matt Damon), "You're such a wowser" when the latter refuses to buy certain types of magazines for him.