A scunder can be a person or a thing. It means a "nuisance". It can be found with several pronunciations. Scunner, Scundered, Scunnered, Scunnert. It is commonly used in ulster (Northern Ireland), Scotland and the North of England.

Intelligence agency term for "psychological operation". A government or corporate-sponsored operation, usually taking the form of a "terrorist attack" or "crazed gunman on a spree", with the intent of panicking the public into demanding more police and laws inhibiting freedom. Psyops are usually carried out by drugging a civilian or group of civilians with aggression-promoting drugs, psyching them up, arming them, and sending them out to commit mayhem. Government-sponsored terrorism. See also blackshirts, conspiracy

Scunder is a word used in Northern Ireland. It is usually used in the past tense 'scundered' as an adjective, although similar in sound to the Scottish 'scunnert' it has its own specific meanning. A neat little phrase sums it up, 'hoisted by your own petard' It is often a personal retort, "That's you totally scundered", perhaps by some sly plan that has backfired.

Derived from the word Scunt which comes from the word cunt.
Scunder has the same meaning as scunt but changed slightly to be more socially acceptable.

Hoisted by your own petard

1: To creep/crawl around in a manner similar to Gollum, usually used in an abstract context when a boy is following a girl around in a club being a creep

Can be used in context to anything unpleasant found crawling around

Under the nuts.