LONDON— What makes a British cultural institution? Style? Sophistication?

In the case of comic magazine Viz, the ingredients are swearing, toilet humor, and biting satire.

Martin Rowson, editorial cartoonist for publications including The Guardian newspaper, calls Viz "magnificently rude, irresponsible, stupid, puerile and brilliant." The magazine has influenced a generation of British humorists and celebrates its 30th birthday with a major exhibition opening Wednesday at London's Cartoon Museum.

Describing Viz is tricky _ especially in a family publication.

It has echoes of classic U.S. humor magazines Mad and National Lampoon, with a dash of The Onion's news parodies. Like "South Park," it exploits the comic potential of potty-mouthed children, and like "The Simpsons" it skewers the mob mentality.

In form, it spoofs the wholesome children's comics of a bygone age _ publications like Beano and Dandy, home of cheeky characters like naughty schoolboy Dennis the Menace.

Viz takes the comic-strip format and adds a scatological, satirical or just plain silly twist. A typical strip might involve the adventures of Black Bag, the Faithful Border Bin Liner _ a loyal, Lassie-like companion who happens to be a plastic garbage bag.

Recurring characters include pompous TV personality Roger Mellie: the Man on the Telly; Finbar Saunders and his Double Entendres; woman-baiting Sid the Sexist; the sanctimonious Modern Parents _ and many others too salty for discussion here.

In the magazine's pages, Britons are drunken, lecherous, conniving and often stupid. Real-life figures _ from rock stars Sting and Bono to Osama bin Laden _ are ruthlessly mocked. There are parodies of tabloid newspapers' obsession with celebrities and aliens, and the long-running column Top Tips, which offers nonsensical nuggets of advice like "Don't waste money buying expensive binoculars. Simply stand closer to the object you wish to view."

"It's in that great tradition of vicious and surreal British humor that includes Monty Python," said writer and broadcaster Charlie Brooker, who cites Viz as a major influence on his own screeds against the idiocy of television.