Yoo Jae Suk and Haha, the comics most famous outside South Korea for Running Man, are resident performers on a hit show at home you might not know.

Infinite Challenge is a more freewheeling and surprising variety show than Running Man, but its humour is less physical and may not cross cultural borders with the same ease.

It is to Running Man what Stephen Chow is to Jackie Chan, effectively. Just as Chow's comedies have translated less well to Hollywood than Chan's action comedies, Infinite Challenge has been more successful at home than abroad.

To a viewer like me, whose tastes run to Chow more than Chan, however, the discovery of Infinite Challenge on Oh!K, a new Korean channel, counts as an event. (Oh!K is affiliated to MBC, the last of Korea's three biggest television stations to have a designated channel in Singapore.)

One of the first Korean shows splicing variety and reality genres, Infinite Challenge plays like a shape- shifter and sometimes a prankster.

A recent episode about the sloppy use of the Korean language sends Yoo, Haha and their four fellow hosts (including Noh Hong Chul, best known as the elevator guy in the Psy music video Gangnam Style) back to school, after an Are You Smarter Than A Fifth Grader?- like studio test shows them to be primary school, kindergarten or tourist- level speakers.

They lunch at a restaurant, only to be taped by the show's secret language police and given charge sheets of their crimes against the Korean language.

Dressed to the nines for what they are told is the celebratory 400th episode, they soon discover they have been lured to a Korean retest with a Fear Factor-style twist. If they fail, they will be lowered into a tank of filthy water and their suits will be ruined.

In its nine years on the air, the show has been a quiz show, a travel show, a music show and a game show, sometimes in the same episode, while riffing on all sorts of pop cultural silliness. (Oh!K is showing vintage episodes as Best Of Infinite Challenge, if you are playing catch-up.)

It has poked fun at the gravitas of gangland films (one episode has the hosts and K-pop group BigBang as rival gangs who have to outwit each other in a life-and-death game of scissors- paper-stone), as well as the talent judge's chair on The Voice (another episode has a chair that faces the stage at a music festival and turns around when the judge doesn't like what he sees).

Neither the format nor the mood is fixed.

The show is free to be as dumb as Running Man (somewhere on YouTube is a video of Haha in an Infinite Challenge episode, submerging his head into an aquarium and catching one octopus after another with his mouth only), but also has the range to encompass contemplation and wistfulness.

I'm thinking of the episodes where Yoo, Noh and Haha go to New York to join Psy on stage at Times Square on New Year's Eve.

Noh is thrilled to bits, even though he has to brave freezing temperatures and perform in the same T-shirt and shorts as in the video to be recognisable to the Americans.

Actually, and amazingly, he is still thrilled the next morning, although he was barely visible on the dark stage beside Psy and got only a few seconds in the spotlight.

It's a moment between funny and sad, which is an unusual place for a prime-time variety show to be.

The Real Men, another MBC hit show on Oh!K, is a what-you-see-is-what- you-get Korean military reality show - testosterone, action, tears and male bonding.

It's old-fashioned stuff - as old as Army Daze and any story about national service as a rite of passage - with new- fangled packaging.

Entertainers do not play recruits but appear as themselves, returning to the army to relive their youth, in the case of actors Kim Su Ro, Jang Hyuk and Ryu Su Young, or trying out their action-hero dreams, in the case of Australian comic Sam Hammington.

Hammington is also the resident overweight guy, because every old-school comedy requires one: especially an action comedy as straightforward as the show's most exciting episodes.

Basically, Hammington suffers arduous training that you get a vicarious ache from watching. But you also have to bite back laughter because he is almost always failing at a routine that Jang, the fittest of the bunch, has performed perfectly minutes ago.

In one episode, Jang demonstrates how to swing across a ditch with a rope, without a stunt double and with the panache of a gymnast. The man is, quite simply, Korean reality TV's Jackie Chan.