From the most recent LRB:
Instead of destroying museums, dissenters... set out to parasitise and subvert them. Duchamp sidestepped the museum when he distributed multiple sets of miniatures of his work, packed in suitcases. Chris Burden's Samson attacks (or at least pretends to attack) the bricks and mortar. His piece consists of a turnstile, a winch, worm gear, a 100-ton jack, timbers and steel plates, designed to be placed in the entrance to a museum. Visitors to the museum drive a glacially slow extension of the timbers which, in theory, threaten to knock down the walls.
I particularly like the idea of Samson. It satirises the idea of the museum by threatening to do exactly what the museum is supposed to be doing: giving public access to the experience of art, in this case by literally exposing them to public view after the collapse of the building. That it does this by the mechanism by which museum itself attempts to achieve this end - visitors coming in, to see the art, and then going out, to take that experience into the world outside the museum - is of course particularly sweet.
Notice though that this depends on the acceptance of the museum's ostensible end. If the joke works, it works because it exposes and exploits a gap between expectation and reality: it relies on the idea that museum exhibitions typically structure the experience of art as passive rather than active, exercise a rather deliberate control over the context in which art is seen and the connections it makes, and that the experience of art shouldn't be like that, as argued for by Phil here. Armando Ianucci is currently giving a series of lectures on British TV Comedy in Oxford (link needed), and I was talking to - or at, more properly, perhaps - one of the people I went with about the way that The Office - or what little I've seen of it - doesn't work because it lacks that gap. Ricky Gervais just is, so far as I can see, David Brent: he doesn't have any appreciation of how he's failed to live up to some norm or moral standard, which means that he can't play with the gap between the actual and the ideal at all, because there doesn't seem to be one.
I suppose this explains much of different people finding different things funny. What's funny depends on the moral universe you inhabit, because it depends on what counts as failing to live up to expectations. Your moral universe, I think, also structures who you think of as the legitimate source material for jokes, who should be exposed for failing to live up to the relevant moral expectations. After all, each joke uses the critical resources of that moral universe to launch an implicit attack on whomever it mocks, and whom you think is a legitimate target of public condemnation, by whom, and on what grounds are a series of interlinked and explicitly moral questions.